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Factors affecting estrogen excretion in dairy heifers

Heather Ashley Tucker

Thesis submitted to the faculty of the Virginia Polytechnic Institute and State University

in partial fulfillment of the requirements for the degree of

Master of Science

In

Dairy Science

Committee:

Katharine F. Knowlton, Committee Chair

R. Michael Akers

J. Reese Voshell, Jr.

July 28th, 2009

Blacksburg, Virginia

Key words: dairy heifer, estrogen, estrous, phytoestrogen

Factors affecting estrogen excretion in dairy heifers

Heather Ashley Tucker

ABSTRACT

Two studies were conducted to assess factors affecting estrogen excretion in

dairy heifers. The objective of the first study was to quantify estrogenic activity in feces

and urine during the estrous cycle. Ten non-pregnant Holstein heifers were fed the

same diet for 28 d. Plasma, feces, and urine samples were collected daily. Plasma 17-β

estradiol (17-β E2) was quantified with RIA and used to confirm day of estrous. Feces

and urine samples from days -12, -6, -2, -1, 0, 1, 2, 6, 12 of the estrous cycle were

analyzed with RIA and Yeast Estrogen Screen (YES) bioassay. Plasma 17-β E2

concentrations peaked on day of estrus, with feces and urine estrogenic excretion

peaking a day after. The objective of the second study was to quantify variation in

estrogenic activity in feces and urine due to increased dietary phytoestrogen content.

Ten Holstein heifers were randomly assigned to treatment sequence in a two-period

crossover design. Dietary treatments consisted of grass or red clover hay, and

necessary supplements. Feces and urine samples were collected and pooled for

analysis. Estrogenic activities of pooled samples were quantified using the YES

bioassay. Estrogenic excretion in feces and urine was higher for heifers fed red clover

hay. Fecal and urine samples from five heifers were analyzed using LC/MS/MS to

quantify excretion of phytoestrogenic compounds. Heifers fed red clover hay excreted

more equol than heifers fed grass. Identifying sources of variation in estrogenic activity

of manure will aid in the development of practices to reduce environmental estrogen

accumulation.

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Key words: dairy heifer, estrogen, excretion, phytoestrogen

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ACKNOWLEDGMENTS

I would like to extend a sincere thank you to my committee members for their

guidance and support over the past two years. To my major advisor, Dr. Knowlton, you

have molded me into a student and researcher I never thought was possible. Your

passion, drive, and love of research inspired me to do my best. Dr. Akers, your

enthusiasm and interest in research, as well as support are deeply appreciated. Finally,

Dr. Voshell, thank you for stepping outside the world of entomology to learn about cows

and support my research endeavors.

There are far too many people in the Dairy Science department to thank. I have

never been part of a department that feels more like a family. Thank you Becky and

Cindy for listening and providing keys to my office for appropriate barn attire acquisition.

Dr. Hanigan, thank you for always making time to answer my questions, reassure me

that I could do it, and that this is all part of learning. I learned so much from working with

you as your graduate teaching assistant, I appreciate the wealth of knowledge you

passed on to me, and the faith you put into me to actually teach students nutrition. To

the farm crew, thank you so much for your assistance and willingness to work with me.

As for the lab, Karen Hall, I have no idea what I would have done without you.

Your willingness to listen, skill in telling me to breath, and desire to learn alongside me

make you the best lab technician a graduate student could ask for. Zhao your ability to

teach me the YES assay made my research, and I am forever indebted to you. Partha

and Jamie, thank you for your help carrying out my research. For all of the Knowlton

Lab undergrads thank you so much, I wish you all the best in life and hope that you find

something that you truly love.

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Friends are something that a person should never be without and I have truly

been blessed to meet some great people during this two year journey. Sarah Blevins,

from the times we spent in Stats making up names for fake meat to the craziness that

consumed us during thesis writing, I heart you. Steph Masiello, I am so glad you strolled

into my life second semester. Thanks for accompanying Sarah and I on our crazy drives

around the drill field blaring Journey and always being up for an adventure. Just

remember we cannot make this stuff up, I think at some point we will look back on this

time and laugh. I wish you two the best and hope that you will always stay in my life.

Brad Henry once said “Families are the compass that guides us. They are the

inspiration to reach great heights, and our comfort when we occasionally falter.” Mom

and Dad, thank you for your unconditional love and support throughout this process.

You have been more than understanding, always there to listen, and provide affirmation

that I could do this. You allowed me to reach for the stars while fulfilling my dreams and

never once faltered in your support. Eric thanks for constantly being my older brother

and offering up Tracy and your home for whenever I needed to get away.

Finally, I never knew that once I walked into the UNH Dairy Barn my path in life

would change. Nancy Whitehouse, thank you for my introduction to dairy nutrition

research. Dr. Fairchild, your strength while battling cancer and tenacity for life inspired

me. Who would have thought that the walk we took around the barn would change my

life. With a few words, you opened my eyes up to the world of research and I have

never looked back, I will thank you every day of my life for that.

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TABLE OF CONTENTS

ABSTRACT ......................................................................................................................ii

ACKNOWLEDGMENTS ..................................................................................................iv

TABLE OF CONTENTS ..................................................................................................vi

LIST OF TABLES .......................................................................................................... viii

LIST OF FIGURES ..........................................................................................................ix

ABBREVIATION KEY ...................................................................................................... x

Chapter 1: Introduction .................................................................................................... 1

Chapter 2: Review of Literature ....................................................................................... 3

Estrogens ..................................................................................................................... 3

Synthesis ....................................................................................................... 3

Secretion ....................................................................................................... 4

Metabolism .................................................................................................... 5

Excretion ....................................................................................................... 6

Endocrine Disrupting Chemicals ................................................................................... 8

Estrogenic EDCs ........................................................................................... 9

EDCs and the dairy industry ........................................................................ 10

Phytoestrogens ........................................................................................................... 10

Phytoestrogen classes ................................................................................ 11

Phytoestrogens in feedstuffs ....................................................................... 13

Methods for detecting estrogenic activity .................................................................... 16

Radioimmunoassay ..................................................................................... 16

Bioassays .................................................................................................... 17

Summary and next steps ............................................................................................ 18

REFERENCES ........................................................................................................... 26

Chapter 3: Effect of the estrous cycle on fecal and urinary estrogen excretion ............. 33

ABSTRACT ................................................................................................................ 33

INTRODUCTION ........................................................................................................ 34

MATERIALS AND METHODS .................................................................................... 35

Sample collection ........................................................................................ 35

Sample processing and analysis ................................................................. 35

Yeast Estrogen Screen (YES) bioassay ...................................................... 37

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Calculating daily excretion ........................................................................... 38

Statistical analysis ....................................................................................... 40

RESULTS AND DISCUSSION ................................................................................... 40

Estrogen and estrogenic activity .................................................................. 40

Differences in quantification by RIA and YES .............................................. 43

CONCLUSIONS ......................................................................................................... 45

ACKNOWLEDGEMENTS ........................................................................................... 45

REFERENCES ........................................................................................................... 46

Chapter 4: Effect of diet on fecal and urinary estrogen excretion .................................. 55

ABSTRACT ................................................................................................................ 55

INTRODUCTION ........................................................................................................ 57

MATERIALS AND METHODS .................................................................................... 58

Total Collection ............................................................................................ 58

Sample Processing and Analysis ................................................................ 59

Yeast Estrogen Screen (YES) Bioassay ..................................................... 60

LC/MS/MS analysis ..................................................................................... 61

Statistical Analysis ....................................................................................... 62

RESULTS AND DISCUSSION ................................................................................... 63

Effect of diet on estrogenic activity of feces and urine ................................. 63

Differences in quantification by YES bioassay and LC/MS/MS ................... 66

CONCLUSIONS ......................................................................................................... 67

ACKNOWLEDGEMENTS ........................................................................................... 68

REFERENCES ........................................................................................................... 68

Appendix A .................................................................................................................... 77

Protocol for 125Iodine Estradiol Radioimmunoassay ................................................... 77

Appendix B .................................................................................................................... 82

Protocol for Yeast Estrogen Screen (YES) Bioassay ................................................. 82

Appendix C .................................................................................................................... 87

Protocol for LC/MS/MS anlaysis of phytoestrogens .................................................... 87

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LIST OF TABLES

Table 2.1 Summary of research on estrogen excretion by cows. .................................. 22

Table 3.1 Ingredient composition of diet. ....................................................................... 49

Table 3.2 Effect of day of estrous on estrogen concentrations. ..................................... 51

Table 3.3 Effect of day of estrous on estrogen excretion and 17-β pool size. ............... 53

Table 4.1 Ingredient composition of study diets. ........................................................... 71

Table 4.2 Effect of diet on DMI, DM digestibility, and excreta output. ........................... 72

Table 4.3 Effect of diet on estrogenic activity and excretion of estrogenic equivalents in

feces and urine. ............................................................................................. 73

Table 4.4 Effect of diet on excretion of phytoestrogenic compounds in excreta as

determined by LC/MS/MS. ............................................................................ 74

Table 4.5 Effect of diet on phytoestrogenic compounds in feed and excreta as

determined by LC/MS/MS. ............................................................................ 75

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LIST OF FIGURES

Figure 2.1 Structure of selected estrogens. ................................................................... 20

Figure 2.2 Biosynthesis of 17-β estradiol. ..................................................................... 21

Figure 2.3 Structure of selected phytoestrogens. .......................................................... 23

Figure 2.4 Synthesis and degradation of the isoflavonoids daidzein and genistein. ...... 24

Figure 2.5 Biosynthesis and metabolic conversion of lignans. ...................................... 25

Figure 3.1 Sample selection for RIA and YES analysis. ................................................ 50

Figure 3.2 Effect of day of estrous on estrogen concentrations in dairy heifers. ........... 52

Figure 3.3 Effect of day of estrous on estrogen excretion and 17-β E2 pool size in dairy

heifers. ......................................................................................................... 54

Figure 4.1 Effect of period on fecal estrogenic activity. ................................................. 76

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ABBREVIATION KEY

17-β E2: 17-β estradiol

17-α E2: 17-α estradiol

AAW: apparently absorbed water

BMPs: best management practices

CPRG: chlorophenol red-β-D-

galactopyranoside

E1: estrone

E2: estradiol

E3: estriol

E2-EDC: estrogenic endocrine

disrupting chemical

E2-eq: 17-β estradiol equivalents

EDC: endocrine disrupting chemical

ER: estrogen receptor

FSH: follicle stimulating hormone

FW: fecal water

FWI: free water intake

GnRH: gonadotropin releasing hormone

hER: human estrogen receptor

iNDF: indigestible neutral detergent fiber

LH: lutenizing hormone

LSM: least squares means

MCF-7: human breast cancer

RIA: radioimmunoassay

SDG: secoisolariciresinol diglycoside

TWI: total water intake

UO: urine output

YES: yeast estrogen screen

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Chapter 1: Introduction

The United States Environmental Protection Agency declared in 2003 that animal

feeding operations are a major environmental concern (EPA, 2003). Many of these

animal feeding operations are under strict guidelines, such as the Effluent and

Limitations Guidelines and Standards under the Clean Water Act, limiting their ability to

manage wastes (EPA, 2003). Better understanding of the effects of diet and

physiological status on estrogenic excretion will aid in developing practices aimed at

reducing environmental accumulation of contaminants.

Among other contaminants, manure from dairy operations contains various

hormones (Lange et al., 2002; Hanselman et al., 2003; Lorenzen et al., 2004).

Hormones are chemicals synthesized from glands in the endocrine system, excreted in

urine and feces, and can have potent environmental effects (Crisp et al., 1998). When

these hormones enter surface water they may functionally alter or disrupt the endocrine

system of those organisms exposed to them (Nichols et al., 1997; Finlay-Moore et al.,

2000; Jenkins et al., 2006,). Such hormones are known as endocrine disrupting

chemicals (Crisp et al., 1998). Estradiol is one of the most potent naturally secreted

estrogens, and is produced by the ovaries. It is also widely recognized as being

responsible for growth and reproductive impairment in aquatic species when discharged

into water (Harrison et al., 1995; Crisp et al., 1998).

Characterizing estrogen excretion patterns by bovines will allow assessment of

the impact of dairy farms on estrogen accumulation in the environment. Evaluation of

the effects of physiological states and diet formulations on estrogen excretion is

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necessary for development of best management practices, to reduce estrogen loss from

dairies.

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Chapter 2: Review of Literature

ESTROGENS

Estrogens are natural hormones synthesized and secreted by the gonads of a

variety of different animals (Behl, 2001). Estrogens are responsible for the normal

growth and development of the female reproductive tract. Estrogen controls the estrous

and menstrual cycle and inhibits the anterior pituitary’s production of gonadotropin

(Gower, 1979).

As part of their four-ring molecular structure, natural steroidal estrogens contain

an aromatic A- and D-ring structure from which key structural differences arise. These

structural differences allow for the addition of functional groups on the C-16 and C-17

positions. Estrone (E1) has one hydroxyl group on C-3, estradiol (E2) has an additional

hydroxyl group on C-17, and estriol (E3) has additional hydroxyl groups on C-16 and C-

17 (Figure 2.1) (Hanselman et al., 2003). Potency varies with chemical structure

causing 17-β estradiol (17-β E2) to be the most potent natural estrogen; E1 has a

relative potency to 17-β E2 of 0.38 and E3 has a relative potency to 17-β E2 of 2.4x10-3

(Rutishauser et al., 2004). Structural differences exist between 17-α estradiol (17-α E2),

where the C-17 hydroxyl group is in the trans configuration, and 17-β E2, where the C-

17 hydroxyl group is in the cis configuration (Figure 2.1). Natural estrogens are slightly

soluble in water, moderately hydrophobic, and are weak acids (Hanselman et al., 2003).

Synthesis

Commonly the term “estrogen” is used to describe the natural endogenous

hormone, E2, which is secreted by selected endocrine glands and travels through the

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blood in relatively low concentrations to specific target tissues (Behl, 2001). The major

sources of estrogen in mammals are the granulosa cells of the ovarian follicles, and

during pregnancy, the placenta (Lange et al. 2002). Additional sources of estrogen are

adipose tissue, the adrenal cortex, the hypothalamus, the kidney, the liver, and muscle

(Fotherby, 1984). Estrogen is synthesized from cholesterol in two separate pathways as

shown in Figure 2.2 (Bidlingmaier and Knorr, 1978).

Falck (1959) was the first to observe that different ovarian cell types interact to

produce E2. Granulosa cells in cows are capable of producing E2 only when an

aromatizable substrate is present or when co-cultured with thecal tissue (Hansel and

Convey, 1983). E2 results from the multi-step conversion of cholesterol to

androstenedione in the theca interna cell, while androstenedione converts to E2 in the

granulosa cell (Hansel and Convey, 1983).

Estrogen production and secretion is pulsatile due to pulsatile secretion of

gonadotropin releasing hormone (GnRH), lutenizing hormone (LH), and follicle

stimulating hormone (FSH). Secretion of estrogen occurs via the hypothamalus-

pituitray-ovary-uterus axis. Hypothalamic release of GnRH causes the release of FSH

and LH from the anterior pituitary. FSH and LH then stimulate the granulosa and theca

interna cells in the follicle of an ovary to synthesize E2 and E1 for release (Behl, 2001).

Secretion

E2 is secreted from the ovaries in response to gonadotropin release from the

pituitary (Behl, 2001). E2 must be transported from the ovaries to its target tissue

through the circulatory system. E2 travels in two forms in the circulatory system, free

and bound, with only a small percentage being in the free form (Bidlingmaier and Knorr,

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1979; Behl, 2001). The majority of E2 in the circulating blood is bound to β-globulin, a

plasma protein that binds both E2 and androgens (Bidlingmaier and Knorr, 1979). E2

binding to these carrier proteins prevents random diffusion into organs, tissues, or blood

vessels which would elicit inappropriate responses, and also prevents rapid metabolism

(Bidlingmaier and Knorr, 1979; Behl, 2001). Once E2 reaches its target tissues, it

produces various effects on developmental, growth, and reproductive bodily functions

(reviewed elsewhere, e.g. Crisp et al., 1998).

Estrous Cycle

Development of estrous behavior in the bovine is a result of the action of E2 (Britt

et al., 1986). Blood E2 concentrations increase during proestrus and estrus and then

rise again during the early luteal phase (Henricks et al., 1971; Hansel and Echternkamp,

1972; Glencross et al., 1973; Chenault et al., 1975; Ireland et al., 1984). One or two

large follicles persist on an ovary during the transition from proestrus to estrus and for

several days after ovulation to mid-diestrus. During metestrus the follicle present during

estrus ovulates, while the other follicles present during diestrus undergo atresia (Dufour

et al., 1972; Matton et al., 1981). A follicle with high concentrations of E2 in its follicular

fluid develops and is “estrogen-active”. The “estrogen-active” follicle is responsible for

most of the E2 secreted during metestrus and diestrus (Ireland and Roche, 1982;

Ireland et al., 1984).

Metabolism

Once E2 is released from the ovaries and reaches and affects the appropriate

target tissues, it re-enters circulation in the blood stream for catabolism and excretion.

Estrogens pass through a series of metabolic pathways in the kidney, liver, and

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gastrointestinal tract (Zhao et al., 2008). E2 and E1 are catabolized to form catechol

estrogens. Catechol estrogens catabolize to methoxyderivatives of the catechols with

the action of O-methyl-transferases. These methoxyderivatives enter into a final

metabolism step in which conjugating enzymes, glucoronyltransferases and

sulfotransferases, catalyze formation of glucorindes and sulfates, increasing the

solubility of the estrogenic compounds in water. This allows for excretion of conjugated

estrogens in urine (Behl, 2001; Shore and Shemesh, 2003).

The estrogens that are not excreted in urine pass to the liver, concentrating in

bile (Pearlman et al., 1947). In the liver estrogens undergo hepatic conversions

including metabolism and conjugation. While in the liver estrogens can be converted

into six families of compounds: glucuronides, catechols, sulfates, fatty acid esters,

hydroxylated metabolites, and E1 (Zhu and Conney, 1998). Once metabolized and

conjugated via enterohepatic circulation, estrogens are excreted into the bile or are

reabsorbed by the gastrointestinal tract. Enterohepatic circulation of estrogens delays

excretion from the body allowing for additional metabolism of the estrogen by micro-

organisms in the intestine and the intestinal mucosa (Fotherby, 1984).

Excretion

Estrogen excretion rates and routes differ by species. It is estimated that the

United States dairy cow population excretes 80 tons of E2 per year (2060 �g/cow/d),

while the pig population excretes 8 tons E2 per year (290 �g/pig/d), and the human

population excretes 3 tons E2 per year (30 �g/human/d) (Johnson et al., 2006).

Furthermore, it has been estimated that land application of livestock manure accounts

for greater than 90% of the total estrogens in the environment (Khanal et al., 2006).

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Studies utilizing radiotracers have shown that cattle excrete 58% of estrogens in their

feces and 42% in their urine, whereas swine excrete 4% in their feces and 96% in their

urine, and poultry excrete 31% in their feces and 69% in their urine. In cattle, 17-α E2,

17-β E2, and E1 account for more than 90% of the estrogens excreted in free or

conjugated forms (Hanselman et al., 2003).

Total E2 excretion by cattle is significant, but there is little quantification data

available (Zhao et al., 2008). In the past, studies aimed at quantification of E2 excretion

were primarily to establish tests used for fertility control and pregnancy diagnosis.

Studies focused on hormonal changes occurring during estrus and pregnancy in older

animals (Hanselman et al., 2003). These studies often used “ambiguous quantification

methods” (Hanselman et al., 2003) relying on colorimetric techniques,

radioimmunoassay, bioassays, and enzyme immunoassays making determining a

reliable value for estrogen excretion for cattle difficult (Table 2.1) (Hanselman et al.,

2003; Johnson et al., 2006).

Estrogen Excretion and Physiological States

Hoffmann et al. (1997) characterized estrogen production and metabolism during

bovine pregnancy. They observed that during pregnancy hormonal changes were

significant enough to affect estrogen excretion in dairy cows. These hormonal changes

resulted in relatively high concentration of E2 measured in feces that were unexpected.

The low blood plasma E2 concentrations measured suggest that blood E2 is not only

conjugated but oxidized and epimerized prior to excretion. Their research illustrates the

need for a parallel between lactation and estrous cycles of the bovine, while expanding

current knowledge regarding E2 excretion (Hoffmann et al., 1997).

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Gaverick et al. (1971) addressed estrogen production and excretion differences

with age. They observed that heifers excreted more 17-α E2 and less 17-β E2 during the

estrous cycle than cows. Average excretion of E1 and total E2 in urine and E2

concentrations in plasma were similar for heifers and cows (Gaverick et al., 1971).

Excretion of total estrogen during the initial estrus for heifers was higher (59 � 15 ng/mg

creatinine) when compared to cows (27 � 5 ng/mg creatinine) but excretion during the

second estrus were similar (29 � 9 ng/mg creatinine for heifers and 34 � 10 ng/mg

creatinine for cows). During the estrous cycle, heifers excreted 33% of total estrogens

as 17-α E2 and 27% as 17-β E2. Cows excreted 21% of total estrogens as 17-α E2 and

42% as 17-β E2 during the estrous cycle (Gaverick et al., 1971). The differences in 17-β

E2 excretion, the major estrogen produced by the ovaries, between heifers and cows

led Gaverick et al. (1971) to conclude that heifers metabolize estrogen more completely

than cows at most stages of the estrous cycle.

ENDOCRINE DISRUPTING CHEMICALS

An endocrine disrupting chemical (EDC) is any chemical that has the capability to

interfere with the production release, transport, metabolism, or elimination of the natural

hormones in the body responsible for the regulation of developmental processes (Crisp

et al., 1998). EDCs are from a variety of different chemical classes, including pesticides,

synthetic hormones, natural plant compounds, and various waste products from industry

(Carr and Norris, 2006). EDCs can accumulate in the environment in numerous ways

including the human use of pharmaceuticals, use of pesticides in farming practices, and

land application of manure from animal operations (Crisp et al., 1998). Once EDCs

enter and accumulate in the environment they have the potential to cause abnormalities

9

in various wildlife species (Colucci et al., 2001). Growing concern surrounds

accumulation of these EDCs in the environment, making identifying the sources of these

contaminants neccessary.

Exposures to EDCs early in development causes feedback mechanisms to be

absent in the mature individual producing severe reproductive and developmental

impairments that hinder the individual (Crisp et al., 1998). Effects of exposure have

been seen in numerous aquatic wildlife populations with a variety of species being

affected. For instance hydroxylated polychlorinated biphenyls and estradiol cause sex

reversal in male turtle embryos. Also, DDT has resulted in feminization of gulls in ovo. A

third example is developmental exposure to environmental estrogen or antiandrogens

altering ratios of estrogen and testosterone in alligators (Sonnenschein and Soto, 1998;

McLachlan, 2001). While negatively affecting the organization of reproductive, immune,

and nervous function of individuals, the sublethal effects of endocrine disruption leads to

long term detrimental consequences in populations (Crisp et al., 1998). Though

exposure to EDCs can cause detrimental effects in a population, it is clear that

exposure during development results in the greatest impact on an individual (Welshons

et al., 2003).

Estrogenic EDCs

EDCs that have estrogenic activity are among the largest groups of known

endocrine disruptors. Estrogenic EDCs (E2-EDCs) are chemicals that act as hormone

mimics through the estrogen receptor (ER) mechanism. For E2-EDCs to have a direct

estrogenic effect in a cell, the cell must possess an ER. ERs can be present in a

number of cellular structures including the nucleus, cell membrane, or cytoplasm

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(Welshons et al., 2003). E2-EDCs need to have a binding affinity for the subtype of the

ER, α or β, in a particular cell (Welshons et al., 2003).

EDCs and the dairy industry

EDCs and their possible impact on the environment and animal populations is an

active area of research area. With the United States Environmental Protection Agency

still developing methods for detection and identification of EDCs, the sheer abundance

of EDCs in the environment is unknown (Degen and Bolt, 2000). In a review by Colborn

et al. (1993) chemicals, reported to have an endocrine disrupting effect and that are

widely distributed in the environment, were summarized. These chemical classes

included pesticides, fungicides, insecticides, nematocides, hormones (synthetic and

natural), and industrial chemicals (Colborn et al., 1993). With over 87,000 compounds

needing to be screened for EDC properties, the focus of research is on establishing a

data base on endocrine disruptors such as the Endocrine Disruptor Knowledge Base

(EDKB) created by the Food and Drug Administration, which lists over 3,000 individual

EDCs (Tong, 2009). Among other contaminants, manure from dairy operations contains

various hormones (Lange et al., 2002; Hanselman et al., 2003; Lorenzen et al., 2004).

Furthermore, it has been estimated that land application of livestock manure accounts

for greater than 90% of the total estrogens in the environment (Khanal et al., 2006). The

percentage of EDCs that are estrogens in unknown, and more work needs to be done in

this research area.

PHYTOESTROGENS

Phytoestrogens are naturally occurring elements of plants that initiate E2-like

effects in animal tissue, although classically defined as compounds exerting estrogenic

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effects on the central nervous system, inducing estrus, and stimulating growth of the

female reproductive tract (Figure 2.3). The E2-like effects of phytoestrogens are induced

by binding to an ER and induction of specific estrogen-responsive gene products

(Mazur, 2000). Phytoestrogens bind to an ER and act as E2 mimics and antagonists

because of the molecular similarity of the phenyl ring to E2 in mammals. Phytoestrogens

act differently depending on the tissue, ER present, concentration of circulating

endogenous E2, and their agonist or antagonist nature (Beck et al., 2005).

The variety of phytochemicals classified as E2-EDCs continues to rapidly expand

(Vajda and Norris, 2006). In 1954 Bradbury and White classified 53 plants as having E2

activity affecting estrus in animals. In 1975 Farnsworth and coworkers expanded that list

to include more than 300 plants. Phytoestrogens are a class of phytochemicals

researched due to reported negative reproductive effects in ruminant females, attributed

to the low concentrations of phytoestrogens eliciting subclinical effects and clinical

outbreaks of estrogenism (Smith et al., 1979; Adams et al., 1988; Adams, 1995).

Phytoestrogen classes

Phytoestrogens can be divided into four main classes: isoflavones, coumestans,

stilbenes, and lignans. All of these are diphenolic compounds with structures similar to

those of natural and synthetic E2 (Kurzer and Xu, 1997; Cornwell et al., 2004). These

structural similarities allow phytoestrogens to mimic or antagonize E2, while adding to

their diversity. The vast diversity of phytoestrogens causes each compound, in its

particular class, to affect the E2-mediated response in a number of ways (Cornwell et

al., 2004).

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Isoflavonoids

Isoflavonoids are the most well known of the phytoestrogens. They are

comprised of a very large and distinctive subclass of flavonoids and include daidzein

and genistein (Mazur, 2000; Cos et al., 2003; Ososki and Kennelly, 2003). Structurally

different from other classes of flavonoids in that one phenyl ring has shifted from the C-

3 position to the C-2 position, isoflavonoids are primarily found in the Fabaceae family,

but have been found in the Iridaceae and Euphorbiaceae families in soy and red clover

extracts (Mazur, 2000; Ososki and Kennelly, 2003; Cornwell et al., 2004). Isoflavonoids

exist as glycosides, which are hydrolyzed in the gut or through processing, or as

aglycones, resulting from the hydrolization of glucosides (Figure 2.4) (Cornwell et al.,

2004). The new compounds that are formed from the metabolism of various

isoflavonoids may have very different biological effects (Ososki and Kennelly, 2003).

Coumestans

Coumestans’ estrogenic activity was first discovered by Bickoff et al. (1957). It

has since been isolated from various clover species and alfalfa, with the potent

phytoestrogenic coumestans being coumestrol and 4’-methoxycoumestrol, found in

legumes and are especially high in various clover species. Coumestrol content varies in

plant material due to plant variety, stage of growth, harvesting practices, disease

presence, location, and occurrence of insect or fungal attack (Ososki and Kennelly,

2003).

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Lignans

Although there are more than 200 naturally occurring lignans, lignans have not

been as thoroughly studied as isoflavones and coumestans. They are present in a

variety of foodstuffs including cereals, fruits, and vegetables (Mazur, 2000; Ososki and

Kennelly, 2003). They have a low molecular weight, are chemically unique, and stable

due to the dibenzylbutane skeleton and positioning of the phenolic group in the meta

position of the aromatic ring (Ososki and Kennelly, 2003). Lignans, a plant phenol

group, result from the joining of two cinnamic acid residues or their biogenetic

equivalents (Figure 2.5) (Mazur, 2000). Plant based lignans convert to mammalian

lignans once they enter into the gastrointestinal tract and undergo various bacterial

actions resulting in the formation of enterolactone and enterodiol (Figure 2.5) (Kurzer

and Xu, 1997). Lignans have not been shown to induce estrus, as other phytoestrogens

do, but have other E2 like actions due to the formation of mammalian lignans resulting in

their classification as phytoestrogens (Kruzer and Xu, 1997).

Stilbenes

Stilbenes are produced through the phenylpropanoid-acetate pathway. The main

dietary source of phytoestrogenic stilbenes is resveratrol from red wine and peanuts.

Resveratrol has two isomers, cis and trans, but only the trans form is estrogenically

active (Cornwell et al., 2004).

Phytoestrogens in feedstuffs

The ability of plant compounds to cause estrus in animals was first documented

during the mid-1920s. However, it was not until the 1940s that red clover, a plant rich in

14

phytoestrogens, was said to have effects on the fertility of grazing sheep (Bennetts et

al., 1946; Adams, 1995). Research has continued in the area but with minimal

investigation into the effect that phytoestrogens have on the total E2 activity of animal

excretions. Past research quantifies particular phytoestrogens with chromatography

methods following the introduction of HPLC in the late 1970s and GC in the 1980s

(Wang et al., 1990; G�ltekin and Yildiz, 2006; Zhang et al., 2007).

High concentrations of phytoestrogens in the diet have effects in numerous

populations. For instance, a high dietary intake of phytoestrogens may be associated

with a reduced incidence of breast and prostate cancer in humans (Smith et al., 1979).

Also, soy-derived phytoestrogens in standard laboratory rat feeds have shown

detectable long term effects (Sharma et al., 1992). A third example is that sheep grazing

on red clover show subclinical estrogenism and reproductive losses in Australia and

New Zealand (Adams, 1995). However, there is minimal data on the effect of

phytoestrogenic diets in bovines. Moreover, research utilizing bioassays to evaluate

feedstuffs has fallen to the wayside, although more sensitive bioassays than the Allen-

Doisy technique (discussed later) are now available, including the Yeast Estrogen

Screen (YES) bioassay (discussed later).

Soybeans

Soybeans (Glycine max) belong to the Fabaceae family of plants and have long

been used as a food source (Ososki and Kennelly, 2003). Soybeans’ isoflavones

content was first recognized in the 1940s and has been extensively researched as

containing phytoestrogens with the first isoflavones isolated being genistin (Walter,

1941; Mazur, 2000; Ososki and Kennelly, 2003). Since then numerous studies have

15

focused on the isoflavone content of soybeans (Murphy et al., 1982; Kiessling, 1984;

Coward et al., 1993; Kaufman et al., 1997; Mazur, 2000). There is large variability in

concentration and composition among different soybeans and soybean products

(Murphy et al., 1982; Franke et al., 1995). Of more importance to the dairy industry

there have also been numerous studies on the effects of industrial processing, such as

roasting time and temperature, and extraction methods, on the isoflavone content of soy

products (Coward et al., 1983; Barnes et al., 1994).

Red Clover

Red clover (Trifolium pretense) is a perennial fabaceous (bean-like) plant native

to the Mediterranean, commonly cultivated in the United States to feed livestock and as

a green manure crop (Booth et al., 2006). The main estrogenic compounds in red clover

are daidzein, genistein, formononetin, and biochanin A, with the latter two being

glycosides (Pope et al., 1953; Schultz, 1965; Adams, 1995; Booth et al., 2006). The

concentration of isoflavones in red clover appears to be under genetic control; however,

environmental factors also affect the concentration of isoflavones (Adams, 1995).

The first reports of reproductive impairments in livestock were made in Australia

and New Zealand in sheep grazing on red clover pasture (Bennetts et al., 1946; Smith

et al., 1979; Adams et al., 1988; Adams, 1995). Researchers concluded that

formononetin is indirectly responsible for the reproductive impairments in livestock,

symptomatic of clover disease (Millington et al., 1964; Adams, 1998). Clover disease is

defined by clinical manifestation of symptoms including impaired fertility, uterine

prolapse, inappropriate mammary development, and inappropriate lactation in unmated

ewes and castrated males (Adams et al., 1998). Additionally, red clover silage

16

containing isoflavones has been reported to cause infertility in cattle (Kallela et al.,

1984).

Extensive studies on the effect of red clover have been done in sheep; however,

there is little research available for its effect on dairy cattle. The metabolism path of

isoflavones in cattle is similar to that of sheep (Braden et al., 1971). Kallela (1968)

observed changes in the reproductive tract of ovariectomized heifers grazing on red

clover similar to the changes seen in sheep populations grazing on red clover pastures.

Yet, cattle appear to be less sensitive to the effects of red clover since the permanent

infertility seen in sheep has not been observed in cattle (Lightfoot, 1974).

The differences in response to phytoestrogens between sheep and cattle may be

due to a more efficient metabolism of formononetin and its metabolites in cattle when

compared to sheep. In addition conjugation of the isoflavones and other estrogenic

compounds to glucuronic acid by the liver as a detoxification step present in cattle may

reduce the plant’s effect. More research in this area is needed (Shutt et al., 1967;

Braden et al., 1971; Cox and Braden, 1974).

METHODS FOR DETECTING ESTROGENIC ACTIVITY

Radioimmunoassay

Radioimmunoassays (RIAs) were first developed by Solomon Aaron Berson and

Rosalyn Yallows in the 1950s to measure insulin concentrations. Since their

development, RIAs have been used in a number of ways in endocrinology research due

to their ability to precisely measure hormone concentrations (Kimball, 2005). RIAs are

based on an antigen-antibody reaction in which a radiolabeled antigen competes with

endogenous antigen from the sample to bind to a specific antibody. Binding is largely

17

based on the assumption that the radiolabeled antigen has the same binding affinity for

the antibody as the endogenous antigen. The bound antigen is then separated from the

free antigen and the radioactivity of the sample is measured (Kimball, 2005).

The benefits of RIAs are that they have a greater sensitivity than other assays.

Quantification of the antigen is in the picogram range using these high affinity

antibodies. RIAs do have limitations, mainly their high cost due to the radioactive

material used, cross-reactivity, and the ability to only detect one compound (Kimball,

2005).

Bioassays

Bioassays are useful tools in determining the estrogenic activity of a variety of

samples. The Allen-Doisy test is the first of the bioassays created to measure

estrogenic activity. Ovariectomized animals (rats and mice) are injected with the

substance to be measured. Administration of the substance can be directly into the

vaginal area, increasing the sensitivity by eliminating circulation and metabolism of the

substance, or injected elsewhere in the body. A vaginal smear technique is utilized to

determine the extent of vaginal cornification, resulting in a relative potency

measurement. The use of this assay has declined due to its inability to differentiate

between estrogens and their antagonists, while also having an unreliable time course

(Allen and Doisy, 1923; Jordan et al., 1985).

A second bioassay used is the human breast cancer (MCF-7) cell line. The MCF-

7 cell line is estrogen sensitive and proliferates in the presence of estrogen. The

increase in cell numbers is the biological equivalent of the increase in mitotic activity in

endometrium of rodents (Soto et al., 1992). The limitations of this assay are that

18

multiple exposures to the estrogenic compound are necessary to elicit a response and

that sample throughput is slow (Breinholt and Larsen, 1998).

A third assay is the YES bioassay. This assay was developed by Routledge and

Sumpter (1996) and has been further modified for use in dairy waste (Zhao et al., 2009).

A recombinant yeast strain (Saccharomyces cerevisiae) containing the human estrogen

receptor (hER) gene and a chromogenic reporter system are utilized for this assay. The

hER gene has been integrated into the chromosome of the strain in which the estrogen

response elements are located on an extrachromosomal plasmid and regulate the

expression of a lacZ reporter gene.

When the estrogen receptor molecule binds with estrogens and estrogen-like

compounds, it co-locates with the estrogen response elements, resulting in β-

galactosidase production. β-galactosidase migrates out of the cell into surrounding

media and is quantified using a chromogenic substrate called chlorophenol red-β-D-

galactopyranoside (CPRG). CPRG turns from yellow to red in response to the reaction

and intensity of the red color quantitatively indicates the amount of estrogenic activity.

Using the YES bioassay yields information on the total estrogenicity of the sample as

estrogenic equivalents (E2-eq) in relation to 17-β E2 (Routledge and Sumpter, 1996).

The YES bioassay is similar in sensitivity but lacks the specificity that RIAs have. This

lack in specificity allows for detection of multiple estrogenic compounds, unlike RIAs,

which is what is environmentally important.

SUMMARY AND NEXT STEPS

Restrictions placed on waste management on animal operations and concern

about environmental accumulation of EDCs resulted in a new body of research.

19

Estrogen, a hormone produced by cows and present in their manure, is one of the

chemicals classified as an EDC. Additional research has led to classification of a variety

of compounds, including phytoestrogens, which mimic estrogen and disrupt the

endocrine system. Red clover is high in phytoestrogens and causes subclinical

estrogenism and reproductive impairments. To assess estrogenic activity a variety of

assays have been developed and improved over time. More work is needed to perfect

and standardize the assays utilized to quantify estrogenic activity, as well as research

on the impact of physiological state and feedstuffs on estrogen excretion. Therefore, the

objectives of this research were:

1. To quantify excretion of estrogenically active compounds during the estrous

cycle.

2. To determine the relationship between plasma 17-β E2 and urine and fecal E2-

eq during the estrous cycle.

3. To quantify excretion of estrogenically active compounds due to feeding a high

phytoestrogen diet.

20

Figure 2.1 Structure of selected estrogens.

Estrone

17-α estradiol

17-β estradiol

Estriol

21

Figure 2.2 Biosynthesis of 17-β estradiol.

22

Table 2.1 Summary of research on estrogen excretion by cows.

Study

Animal Status Total Fecal

Estrogens

Urinary Estrogens

(�g/d/cow)

Erb et al., 1968a

Pregnant

NA1

E1 3600–28,800;

E2β 1200– 3600

Erb et al. , 1968b

Pregnant and

Ovariectomized

NA

11,300–31,464

Desaulniers et al., 1989

Cycling

34 ng/g

NA

Desaulniers et al., 1989

Pregnant

30 – 2000 ng/g NA

Hoffman et al., 1997

Pregnant

10 – 1000 ng/g NA

M�stl et al., 1997

Pregnant

10 – 180 ng/g NA

Hanselman et al., 2003

Review

256 – 7300

�g/d/cow

320 – 104,320

1NA = Not Analyzed

23

Figure 2.3 Structure of selected phytoestrogens.

Biochanin A

Coumestrol

Daidzein

Equol

Formononetin

Genistein

24

Figure 2.4 Synthesis and degradation of the isoflavonoids daidzein and genistein.

25

Figure 2.5 Biosynthesis and metabolic conversion of lignans.

26

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Zhao, Z., Y. Fang, N. G. Love, and K. F. Knowlton. 2009. Biochemical and biological

assays of endocrine disrupting compounds in various manure matrices.

Chemosphere 74:551-555.

Zhu, B. T. and A. H. Conney. 1998. Functional role of estrogen metabolism in target

cells: Review and perspectives. Carcinogenesis 19:1-27.

33

Chapter 3: Effect of the estrous cycle on fecal and urinary estrogen

excretion

ABSTRACT

The United States Environmental Protection Agency has identified estrogens

from animal feeding operations as a major environmental concern, but little data is

available quantifying estrogen excretion by dairy cattle. The objectives of this study

were to quantify estrogenic activity in feces and urine during the estrous cycle in dairy

heifers, and evaluate relationships between excreted estrogens and plasma 17-β

estradiol (17-β E2). Ten non-pregnant Holstein heifers were fed a common diet for the

28 d study. Plasma was obtained via jugular venipuncture and grab samples of feces

and urine were collected daily. Plasma 17-β E2 was quantified with RIA and used to

confirm day of estrous. Feces and urine samples from days -12, -6, -2, -1, 0, 1, 2, 6, 12

of the estrous cycle were analyzed with RIA and Yeast Estrogen Screen (YES)

bioassay. The YES bioassay utilizes a recombinant yeast strain (Saccharomyces

cerevisiae) containing the human estrogen receptor gene and a chromogenic reporter

system to indicate total estrogenic activity. Plasma 17-β E2 concentrations peaked on

day of estrus (22.9 pg/mL), with feces and urine estrogenic activity peaking a day after

plasma 17-β E2 peaked. Excretion values mirrored sample concentrations, with fecal

and urine estrogenic equivalent (E2-eq) excretion peaking on d 1 of estrous (101 mg/d

and 129 mg/d). Identifying sources of variation in estrogen excretion by livestock will aid

in the development of practices to reduce environmental estrogen accumulation.

Key words: estrogen, estrous, feces, urine

34

INTRODUCTION

The United States Environmental Protection Agency declared in 2003 that animal

feeding operations are a major environmental concern due to their concentration of

environmental contaminants (EPA, 2003). Strict guidelines and standards make it

necessary to develop practices that understand the effect of physiological status on

estrogen excretion and to develop practices to reduce environmental accumulation of

contaminants.

Hormones synthesized by glands in the endocrine system are excreted in urine

and feces and may have potent environmental effects if runoff follows land application

(Crisp et al., 1998, Lange et al., 2002; Hanselman et al., 2003; Lorenzen et al., 2004).

When these hormones enter surface water they may functionally disrupt the endocrine

system of organisms exposed to them, making them endocrine disrupting chemicals

(EDCs) (Nichols et al., 1997; Crisp et al., 1998; Finlay-Moore et al., 2000; Jenkins et al.,

2006). Estrogens are widely recognized as being responsible for growth and

reproductive impairment in aquatic species when discharged into water (Harrison et al.,

1995; Crisp et al., 1998,).

Limited data is available quantifying estrogenic excretions from dairy animals.

Hoffmann et al. (1997) characterized estrogen production and metabolism during bovine

pregnancy and observed hormonal changes over time significant enough to increase

estrogen excretion 100 fold in feces and 550 fold in urine during pregnancy. More data

is needed to characterize estrogen excretion, and total estrogenicity of manure, during

other life stages of dairy animals. This data will assist in developing management

practices to control estrogen loss from farms.

35

MATERIALS AND METHODS

Holstein heifers (n=10) averaging 13.3 � 0.8 (SD) m of age and 290.8 � 25.8 kg

BW were fed in a Calan door system in a free stall barn (American Calan; Northwood,

NH). During the 28 d study, all heifers received a common diet consisting of corn silage

and a soybean hull and wheat midds based concentrate to meet the heifers’ nutrient

requirements (NRC, 2001; Table 3.1). Daily feed intakes were recorded. All procedures

and protocols were conducted under the approval of the Virginia Tech Institutional

Animal Care and Use Committee.

Sample collection

Samples of blood, feces, and urine were collected daily at 1100h. Blood samples

were obtained via jugular venipuncture, alternating daily between the left and right

jugular (Becton Dickinson Vacutainer; Franklin Lakes, NJ). Blood was stored on ice until

centrifugation. Grab samples of feces were collected via manual removal from the

ampula recti. Urine samples were obtained through induced micturition. All samples

were placed on ice until sampling was completed.

Sample processing and analysis

Blood

Plasma was harvested via centrifugation (2000 x g for 30 min) and frozen at -

80�C until analysis. At the conclusion of the study, plasma samples were thawed and

extracted using ether (500 �L of plasma + 3.0 mL of ether) in 13x100 test tubes. Tubes

were covered with plastic wrap, vortexed for 2 min, and frozen in a dry ice ethanol bath.

The upper liquid ether phase was poured into clean tubes and evaporated using a

36

gentle stream of air (Oragnomation; Berlin, MA). The ether extraction was repeated, the

sides of the tubes were rinsed using 0.5 mL of ether, and the extract and rinse were

evaporated. Plasma extracts were re-constituted with 100 �L PBS-BSA and vortexed,

covered, and stored overnight at 4�C.

Re-constituted plasma extracts were analyzed with ultrasensitive

radioimmunoassay kit (DSL-4800) to determine concentration of 17-β E2 (Diagnostic

Systems Laboratories INC; Webster, TX). Resulting plasma 17-β E2 concentrations

were plotted by heifer to define individual estrous cycles. The day with the highest

concentration of 17-β E2 was declared d 0 of estrous. Fecal and urine samples from

days -12, -6, -2, -1, 0, 1, 2, 6, and 12 of estrous were selected for further analysis

(Figure 3.1). Three heifers were removed from the sample set because plasma RIA

results indicated that they were pre-pubertal ([17-β E2] < 4.3 pg/mL). Plasma 17-β E2

pool size was calculated as the product of plasma 17-β E2 concentration and estimated

plasma volume (3.5% of BW; Dukes, 1955).

Feces

Feces samples were extracted on the day of collection using a base extraction

technique described by Zhao et al. (2009). In brief, 10 g of wet feces were diluted by

weight with 30 g of water. Aliquots (1.0 mL) of this mixture were placed into 4, 16x100

pyrolyzed glass test tubes and mixed with 1.5 mL of NaOH (1N) and 1.5 mL chloroform

to solubilize the estrogens. Tubes were vortexed twice for 20 s and centrifuged (2500 x

g for 20 min). The upper chloroform phases were pooled; 1.0 mL was aliquoted into 4,

16x100 test tubes and mixed with 180 �L of 90% acetic acid, to lower pH to 4.4, and 3.0

mL toluene. Tubes were vortexed twice for 20 s and centrifuged (2500 x g for 20 min).

37

Samples were stored overnight at -20�C to enhance phase separation. The upper,

toluene phase was decanted into clean tubes and stored at -20�C. The toluene

extraction was repeated on the chloroform phase. Toluene phases were combined,

evaporated to dryness using N2 gas (Organomation; Berlin, MA) to concentrate the

estrogens, and stored at -20�C. Samples from selected days (Figure 3.1) were analyzed

with the RIA and YES bioassay described below.

Urine

Urine samples were extracted on the day of collection using the base extraction

technique described by Zhao et al. (2009) and outlined above. Samples from selected

days (Figure 3.1) were analyzed with the RIA and YES bioassay described below.

Yeast Estrogen Screen (YES) bioassay

Feces and urine samples were analyzed for total estrogenicity using the YES

bioassay following the procedure developed by Routledge and Sumpter (1996) and

modified for use in dairy waste (Zhao et al., 2009). In brief, a recombinant yeast strain

(Saccharomyces cerevisiae) containing the human estrogen receptor (hER) gene and a

chromogenic reporter system was used to measure total estrogenic activity, expressed

as 17-β E2 equivalents (E2-eq). In the recombinant strain, the estrogen response

elements are located on an extrachromosomal plasmid and regulate the expression of a

lacZ reporter gene, which produces β-galactosidase when transcription is activated.

When the estrogen receptor element binds with estrogens and estrogen-like

compounds in the sample of interest, the amount of estrogenic activity can be quantified

by color change due to β-galactosidase (Routledge and Sumpter, 1996).

38

The assay was carried out in a laminar flow hood (Contamination Control INC;

Lansdale, PA). Evaporated sample extracts were re-suspended with 1.0 mL of absolute

EtOH. In sterile flat-bottomed 96-well microtiter plates (Becton Dickinson Labware;

Franklin Lakes, NJ), 100 �L of the re-suspended sample was serially diluted and 10 �L

of each serial dilution was aliquoted in triplicate. Plates were allowed to evaporate to

dryness in air before 200 �L of assay medium containing yeast cells (grown to an

absorbance of 1 at 620 nm) and chlorophenol red-β-D-galactopyranoside (CPRG) were

added to each well (Holbrook et al., 2002). The plates were sealed and incubated at

32�C for 24 h and then at room temperature for 12 h. Color density was quantified by

measuring the absorbance at 575 nm and cellular density was quantified at an

absorbance of 620 nm (�Quant BioTek Instruments, INC; Winooski, VT). Duplicates of

each extracted sample were run on the same plate. Each plate also contained an E2

standard curve (>98% purity, Sigma Chemical Company; St. Louis, MO) ranging from

976 to 125000 ng/mL.

Calculating daily excretion

Daily fecal output

Indigestible Neutral Detergent Fiber (iNDF) was used as a marker for fecal

output. Feed and fecal samples were analyzed for iNDF (Cumberland Valley Analytical

Services, Hagerstown, MD) using a 120 hr incubation period with a double inoculation

of rumen fluid (Tilley and Terry, 1963). Fecal output was calculated with the equation:

Fecal output (kg/d)=

DMI (kg/d)x feed iNDF (%DM)

feces iNDF (%DM)

39

Fecal density was measured using a water displacement technique (Lupton and

Ferrell, 1986) and used to convert estrogen content (wt/vol) to excreted quantities. Daily

fecal estrogenic excretion was then calculated as the product of fecal E2-eq

concentration and fecal output.

Daily urine output

Specific gravity was used to determine daily urine output as described by Holter

and Urban (1992). Specific gravity of urine samples in duplicate acidified (1 mL of 12.1

N HCl per 80 mL of urine) samples was determined with a Midget Urinometer (Fischer

Scientific) (Myers and Beede, 2009). Daily output of urine was calculated as:

Urine Output (UO):

UO kg/d= 212.1 + 0.8822 � DMI (kg/d) - 0.03452 � dietary %DM + 1.001 �

dietary CP (%DM) - 216.4 � urine SG + 0.1414 � AAW

where:

Free Water Intake (FWI):

FWI kg/d= -10.34 + 0.2296 � dietary %DM+2.212 � DMI kg/d + 0.03944

� dietary CP (%DM)

2

Total Water Intake (TWI):

TWI kg/d= 35.19 + 0.9823 � FWI (kg/d) - 0.011 �BW(kg) + 1.0817 � DMI(kg/d)

+ 1.184 � dietary CP(%DM) - 0.03881 � dietary CP(%DM)

2

- 0.9963 �

dietary %DM + 0.005488 � dietary %DM

2

Fecal Water (FW):

FW kg/d= 5.52 + 1.32 � DMI (kg/d) + 0.0384 x dietary %DM

Apparently Absorbed Water (AAW):

AAW kg/d= TWI – FW

(Holter and Urban, 1992)

40

Daily urinary estrogenic excretion was then calculated as the product of urinary

E2-eq concentration and urine output.

Statistical analysis

Plasma 17-β E2 concentration, and concentrations and excretion of 17-β E2 and

E2-eq in feces and urine were analyzed using the Mixed procedure of SAS (9.1, 2003)

with the model:

Yij = � + Hi + Dj + eij

where:

� = overall mean;

Hi = effect of heifer (i = 1 to 7);

Dj = effect of day of estrous cycle (d= -12, -6, -2, -1, 0, 1, 2, 6, 12); and

eij = error (heifer by day interaction)

Data are reported as least squares means (LSM) � SE. Significance was

declared at P < 0.05 and trends at P < 0.10.

RESULTS AND DISCUSSION

Estrogen and estrogenic activity

Plasma 17-β E2 was low (< 2.5 pg/mL) throughout proestrus, metestrus, and

diestrus and peaked at 22.9 pg/mL � 2.4 (Effect of day P < 0.0001; Table 3.2, Figure

3.2); the day of peak plasma 17-β E2 was deemed d 0 of estrous. Fecal 17-β E2 and

urine 17-β E2 were not significantly different throughout the estrous cycle. Fecal and

urine E2-eq concentrations rose in the days leading up to estrus, peaked on d 1 of

estrous (113 �g/mL � 14; 108 �g/mL � 13), and declined after d 1 of estrous (> 10

41

�g/mL). Patterns of daily excretion were similar to daily sample concentrations (Table

3.3, Figure 3.3), peaking at 101 mg/d � 11 (feces) and 129 mg/d � 16 (urine).

There is little published data on estrogen excretion by cattle during estrous.

Using thin layer chromatography and gas liquid chromatography measurement

techniques, Gaverick et al. (1971) observed that urinary estradiol (E2) excretion was

highest on day of estrus (42 ng/mg creatinine) and nearly as high on the day following

estrus (37 ng/mg creatinine) and the 2 days preceding estrus (28 and 29 ng/mg

creatinine). This pattern was not observed in the current study, with distinct increases in

urine and fecal estrogenic activity on the day following estrus.

The observed pattern of plasma 17-β E2 concentrations reflects expected

ovarian release of E2 in response to stimulation of the hypothalamus-pituitary-ovary-

uterus axis to induce estrus, and the luteinizing hormone (LH) surge (Behl, 2001).

During estrus, E2 concentrations spike following ovulation of the Graafian follicle and

then decline to low concentrations throughout the estrous cycle when gonadotropin

concentrations are low (Senger, 1999). The pulse like release of LH and 17-β E2 as well

as secretion coinciding with the triphasic growth of the Graafian follicles may cause

differences in estrogen excretion between animals (Cupps et al., 1959; Asdell, 1960;

Bane and Rajakoski, 1961).

Secretion of estrogens from the ovaries varies during the estrous cycles. As part

of their four-ring molecular structure, natural steroidal estrogens contain an aromatic A-

and D-ring structure from which key structural differences arise. These structural

differences allow for the addition of functional groups on the C-16 and C-17 positions.

E1 has one hydroxyl group on C-3, E2 has an additional hydroxyl group on C-17, and

42

estriol has additional hydroxyl groups on C-16 and C-17 (Hanselman et al., 2003).

Potency varies with chemical structure with 17-β E2 the most potent natural estrogen.

E1 has a relative potency to 17-β E2 of 0.38 and estriol has a relative potency to 17-β

E2 of 2.4x10-3 (Rutishauser et al., 2004). Interconversions occur between various

estrogens, and their half-life varies, likely influencing the estrogenic activity of the

manure following excretion.

Shaikh (1971) characterized secretion rates of estrone (E1) and E2 during the

estrous cycle of rats. He observed that E2 was secreted from the ovaries at a rate of

432 pg/h/ovary during proestrus and metestrus, increasing 11-fold during estrus, and

increasing 4-fold during diestrus (Shaikh, 1971). Henricks et al. (1983) calculated the

half-life of three types of estrogens in cattle: E1, 17-α estradiol (17-α E2), and 17-β E2.

E1 has a half-life of 2.41 h, while 17-β E2’s half-life is 0.84 h, and 17-α E2’s half-life is

0.71 h (Henricks et al., 1983). Secreted estrogens are transformed during metabolism

(details below) and these interconversions and differences in relative potencies of the

estrogens likely influence the estrogenic activity of manure.

In pregnant cows, fecal estrogens have been reported to range from 256 to 7300

�g/cow/d (Hanselman et al., 2003). Using HPLC separation techniques and RIA

quantification, Hoffman et al. (1997) reported that fecal concentrations of E1, 17- α E2,

and 17- β E2 excretion were low in the early days of pregnancy (~ 6 ng/g) and steadily

increased with days of pregnancy, peaking at ~ 100 ng/g 5 d prior to parturition. Fecal

17-β E2 concentration in feces (≤ 1.1 ng/g) were low during the early stages of

pregnancy (-240 to -160 d before parturition). These values are similar to the fecal

43

concentrations reported by M�stl et al. (1984) (10 to 180 ng/g), and less than fecal

concentrations reported by Desaulniers et al. (1989) (20 to 2600 ng/g).

Urinary estrogens range from 320 to 104,320 �g/cow/d (Hanselman et al., 2003).

Erb et al. (1968) observed that total urinary estrogen excretion by pregnant cows

increased throughout pregnancy from 123 to 3,402 �g/h/500 kg BW. Hoffman et al.

(1997) observed low 17-β E2 concentration in urine (< 0.002 ng/mosmol) during the

early stages of pregnancy (-240 to -160 d before parturition), similar to the low

concentrations observed in the current study.

Relative proportions of the different estrogenic compounds vary between urine

and feces. Hoffman et al. (1997) reported that in urine, estrone was the primary

excreted estrogen (89.9% of total estrogens), followed by 17-α E2 (9.1%) and 17-β E2

(1%). In feces 17-α E2 was the primary excreted estrogen (56.7%), followed by 17- β E2

(32%) and E1 (11.3%). These differences account for the similarity in estrogenic activity

of feces and urine samples despite the ~2 fold higher E2 content of feces (Table 3.2).

Differences in quantification by RIA and YES

Observed 17-β E2 concentrations in the urine and feces are lower than the E2-eq

concentrations most likely due to hepatic metabolism. Estradiol is conjugated into six

different families of compounds: glucuronides, catechols, sulfates, fatty acid esters,

hydroxylated metabolites, and E1 (Zhu and Conney, 1998). Hoffman et al. (1997)

characterized urinary and fecal estrogen excretion during various stages of pregnancy.

Utilizing HPLC separation techniques and RIA quantification, they observed that the

estrone (89.9%) was the primary excreted estrogen, followed by 17-α E2 (9.1%) and 17-

β E2 (1%). In feces 17-α E2 (56.7%) was the primary excreted estrogen, followed by 17-

44

β E2 (32%) and E1 (11.3%) (Hoffman et al., 1997). 17-β E2 concentration in feces (< 2.0

ng/g) and urine (< 0.002 ng/mosmol) were low during the early stages of pregnancy (-

240 to -160 d before parturition), similar to the low concentrations observed in the

current study. Estrone sulfate is the major urinary estrogen, while free estrogens are

dominant in the feces (Hoffman et al., 1997).

The lag between peak plasma 17-β E2 onset and peak urine and feces

estrogenic activity may be due to typical metabolism of estrogen within the body.

Estrogens are stored in the liver before passing to the kidney for excretion, or are

conjugated and metabolized then pass into the gastrointestinal tract via bile. Kaltenbach

et al. (1976) used radiolabeled E2 (dpm/10g tissue converted to pg/g) to asses E2

metabolism in heifers and observed greatest radioactivity in the liver and kidney (6,600

pg/g � 1290, 4,740 pg/g � 1390) and lower radioactivity in muscle (360 pg/g � 50).

Clearly the liver and kidney store and concentrate estrogens, releasing them in a

pattern that lags behind rate of secretion. Bacterial conversion in the intestinal tract,

entrance of estrogens into the bowel directly from circulation through the intestinal wall,

and further conjugation and metabolism may also account for the lag pattern of

excretion (Mellin and Erb, 1965).

Literature values are generally lower than those observed in the current study.

This is largely due to the low sensitivity of earlier quantitative techniques, inadequate

purification, and extraction methods (Mellin and Erb, 1965) and most importantly,

differences in target compounds. The YES bioassay detects total estrogenic activity;

while past studies quantified individual compounds with RIA or fluorometric assays. The

appropriate quantification method measure depends on the goal of the study;

45

measurement of total estrogenic activity allows for assessment of relative environmental

risk and may be more useful in development of best management practices (BMPs) to

reduce estrogen losses from livestock farms.

CONCLUSIONS

Fecal and urine estrogenic activity peaked on d 1 of estrous, while there were no

clear patterns for excretion of 17- β E2. The disconnect between observed patterns of

estrogenic activity in excreta during estrous and relatively consistent 17- β E2 content in

those samples is likely due to hepatic and gastrointestinal metabolism of estrogens to

other compounds with estrogenic activity. Bioassay measurements of total estrogenic

activity of manure reflect potential environmental risk more accurately than

measurement of specific estrogenic compounds. Variation in manure estrogens with

physiological status should be considered when instituting BMPs for control of estrogen

losses from farms.

ACKNOWLEDGEMENTS

The authors would like to thank Lee Johnson for assistance with RIA analysis,

Wendell Khunjar for trouble shooting the YES bioassay, and Karen Hall and Matt Utt for

assistance with interpretation. The work of Shane Brannock, Chris Brown, Curtis

Caldwell, Rachael Dunn, Dana Gochenour, Jamie Jarrett, Ashley Jones, Katharine

Pike, Partha Pratim Ray, William Saville, and Abigail Schmidt is greatly appreciated.

46

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49

Table 3.1 Ingredient composition of diet.

Item

% of DM

Ingredients1

Corn silage

35.5

Soybean hulls

19.4

Wheat midds

16.2

Cottonseed hulls

9.71

Corn gluten feed

4.85

Dried distillers grain

4.85

Corn, dried and ground

3.24

Molasses

1.94

Cottonseed meal

1.62

Soybean meal, high protein

1.62

Limestone

0.55

Salt

0.33

Vitamin and Mineral Mix2

0.16

Nutrient composition

CP

14.5

NDF

46.6

ADF

28.3

Ca

0.6

P

0.5

1 All ingredients except corn silage were combined to form a pre mix added

to the corn silage daily.

2 Contained: 43.6% Potassium/Magnesium Sulfate, 25% Selenium, 12.5%

Vitamin E, 6.3% Bovatec, 160,000 mg/kg Zn, 150,000 mg/kg Mn, 4,000

mg/kg Cu, 3,500 mg/kg I, 1,600 mg/kg Co, 26,400 kIU/kg vitamin A, 8,800

kIU/kg vitamin D, and 4,400 kIU/kg vitamin E.

50

Figure 3.1 Sample selection for RIA and YES analysis. Shaded in grey are days of

estrous cycle from which fecal and urine samples were analyzed.

Metestrus

Diestrus

Proestrus

E

s

tru

s

Diestrus

Day of Estrous Cycle

-12 -11 -10 -9

-6

-7

-8

-5 -4 -3 -2 -1

6

5

4

3

2

1

0

8

12

7

11

10

9

51

Table 3.2 Effect of day of estrous on estrogen concentrations.

Day of Estrous Cycle

-12 -6

-2

-1

0

1

2

6

12 SEM1

P-value

Plasma E2 (pg/mL)

1.7 0.9 0.9 1.6 22.9 2.5 1.5

1.1 0.9 2.4 < 0.001

Feces E2 (pg/mL)

10.8 11.4 11.8 14.1 13.6 14.5 23.5 19.4 21.5 1.6

0.87

Feces E2-eq (�g/mL) 11

20 36 79

90 113 90

14 10

14

< 0.001

Urine E2 (pg/mL)

4.9 4.9 3.4 8.1 4.9 5.5 3.4

4.8 3.2 0.5

0.49

Urine E2-eq (�g/mL)

6

17 24 68

82 108 70

15 12

13

< 0.001

1 SEM = standard error of the mean

52

Figure 3.2 Effect of day of estrous on estrogen concentrations in dairy heifers. ■ =

Feces E2-eq (�g/mL); ▲ = Urine E2-eq (�g/mL); ♦ = Plasma E2 (pg/mL).

0

5

10

15

20

25

0

20

40

60

80

100

120

-12

-6

-2

-1

0

1

2

6

12

P

la

s

m

a

1

7

B

-E

2

(p

g

/m

L

)

U

rin

e

a

n

d

F

e

c

a

l E

2

-E

q

(u

g

/m

L

)

Day of Estrous Cycle

53

Table 3.3 Effect of day of estrous on estrogen excretion and 17-β pool size.

Day of Estrous

-12 -6 -2 -1

0

1

2

6 12 SEM1

P-value

Plasma E2 (ng)

19 11 11 18 262

27 18 13

9

15 < 0.001

Feces E2 (ng/d)

10 12 15 17

18

17 29 20 24

2

0.88

Feces E2-Eq (mg/d) 12 24 33 90

95 132 101 14 10

16 < 0.001

Urine E2 (ng/d)

53 54 37 77

56

65 42 56 40

4

0.59

Urine E2-Eq (mg/d)

7 21 30 82 101 129 88 18 15

15 < 0.001

1SEM = standard error of the mean

54

0

50

100

150

200

250

300

0

20

40

60

80

100

120

140

-12

-6

-2

-1

0

1

2

6

12

P

la

s

m

a

1

7

β

-E

2

P

o

o

l S

ize

(n

g

)

U

rin

e

a

n

d

F

e

c

a

l E

2

E

x

c

re

tio

n

(m

g

/d

)

Day of Estrous

Figure 3.3 Effect of day of estrous on estrogen excretion and 17-β E2 pool size in

dairy heifers. ■ = Feces E2-eq (mg/d); ▲ = Urine E2-eq (mg/d); ♦ = Plasma 17-β E2

(ng).

55

Chapter 4: Effect of diet on fecal and urinary estrogen excretion

ABSTRACT

The United States Environmental Protection Agency has identified estrogens

from animal feeding operations as a major environmental concern, but little data is

available quantifying estrogen excretion by dairy cattle. The objectives of this study

were to quantify variation in estrogenic activity in feces and urine due to increased

dietary inclusion of phytoestrogens. Ten Holstein heifers were randomly assigned to

treatment sequence in a two-period crossover design to evaluate the effect of diet on

estrogen excretion. Dietary treatments consisted of grass hay or red clover hay, and

necessary supplements. Total collection allowed for sampling of feed refusals, feces,

and urine during the last 4 d of each period. Feces and urine samples were pooled by

heifer and period and extracted using a base extraction technique, and estrogenic

activity was quantified using the Yeast Estrogen Screen (YES) bioassay. Fecal and

urine samples from five heifers were also analyzed using LC/MS/MS to quantify the

excretion of specific phytoestrogenic compounds. Excretion of estrogenic equivalents in

feces and urine was higher for heifers fed red clover hay (84.4 and 120.2 mg/d) when

compared to those fed grass hay (57.4 and 35.6 mg/d). Liquid chromatography-double

mass spectrometry analysis of feces indicated that heifers fed red clover hay excreted

more equol, genistein, daidzein and formononetin (1634.0, 29.9, 96.3, 162.8 mg/d) than

heifers fed grass hay (340.3, 3.0, 46.2, 18.3 mg/d). Diet had no effect on fecal biochanin

A or coumestrol or any of the phytoestrogens detected in urine (2-carbethoxy-5, 7-

dihydroxy-4’-methoxyisoflavone, daidzein and formononentin). Identifying sources of

56

variation in estrogenic activity of manure will aid in the development of practices to

reduce environmental estrogen accumulation.

Key words: red clover, phytoestrogen, excretion, heifer

57

INTRODUCTION

The effect of dietary inclusion of phytoestrogens on estrogenic excretion needs to

be researched to decrease estrogen losses for farms. High concentrations of

phytoestrogens in the diet have negative reproductive effects in ruminant females,

because of their ability to initiate estrogen-like effects in animal tissue (Smith et al.,

1979; Adams et al., 1988, Sharma et al., 1992; Adams, 1995, Mazur, 2000). When

these chemicals enter surface water they may functionally disrupt the endocrine system

of organisms exposed to them, making them endocrine disrupting chemicals (EDCs)

(Nichols et al., 1997; Crisp et al., 1998; Finlay-Moore et al., 2000; Jenkins et al., 2006).

Phytoestrogens are widely recognized as being responsible for growth and reproductive

impairment in aquatic species when discharged into water (Harrison et al., 1995; Crisp

et al., 1998,).

Research on phytoestrogens is extensive but the effect of phytoestrogens on the

total estrogenic activity of animal excretions has not been assessed. Shutt et al. (1970)

observed that feeding red clover, a plant high in phytoestrogens, to sheep increased

excretion of phytoestrogens in feces and urine. With Shutt et al. (1970) focused on

metabolism of phytoestrogens in the rumen rather than excretion, minimal data is

provided about estrogenic activity of the manure. Moreover, there is limited published

work in cows and research utilizing bioassays to evaluate feedstuffs for estrogenic

activity has fallen to the wayside, although more sensitive bioassays are now available.

Therefore, the objectives of this study were to evaluate the effect of diet on the

estrogenic activity of feces and urine, and to quantify the excretion of estrogenically

active compounds.

58

MATERIALS AND METHODS

Holstein heifers (n=10) averaging 18.1 � 1.7 (�SD) m of age, 103 � 16.9 d

pregnant, and 413.9 � 44.5 kg BW were randomly assigned to a treatment sequence

and balanced for days pregnant and age in a two-period crossover design. Dietary

treatments consisted of grass hay or red clover hay, with a fixed amount of a byproduct-

based concentrate to meet the heifers’ nutrient requirements (NRC, 2001; Table 4.1).

The experiment consisted of two periods, each lasting 14 d. The first 10 d served as an

acclimation period to the diet followed by 4 d of total collection. During diet acclimation

heifers were fed in a Calan door system in a free stall barn (American Calan;

Northwood, NH) and feed offered was recorded daily. All procedures and protocols

were conducted under the approval of the Virginia Tech Institutional Animal Care and

Use Committee.

Total Collection

Total collection of feed refusals, feces, and urine was conducted during the last 4

d of each period, with four, 24 h total collections during each period. On d 9 of the diet

acclimation period heifers were fitted with a urinary catheter (22 French, 75 cc; C.R.

Bard, Inc., Covington, GA) and moved into metabolism stalls for a 24 h adaptation to

both the metabolism stall and the catheter. The urinary catheter was connected to

Tygon tubing (Saint-Gobain Performance Plastics, Mickelton, NJ) that drained into a

sealed, clean plastic 12 L jug. Every 6 h, feces were removed from behind the heifer

and placed into plastic containers. Feces and urine were weighed daily, mixed

thoroughly, and sub-sampled. All excreta samples were stored at -20�C until analysis.

59

Feed offered and refused was recorded during the collection periods and feed was

sampled on the final day of total collection.

Sample Processing and Analysis

Feed

Feed samples were collected on d 4 of total collection. Samples were dried at

60�C to a constant weights and then ground through a 1 mm screen in a Wiley mill

(Arthur A. Thomas, Philadelphia, PA). These samples were then analyzed in duplicate

for K, Cl, Na, P, Ca, and Mg (AOAC, 1984).

Feces

Daily fecal samples were pooled to one sample per collection period, weighted

by daily excretion (wet basis) for each heifer, then extracted using a base extraction

technique described by Zhao et al. (2009). In brief, 10 g of feces were diluted with 30 g

of water. Aliquots (1.0 mL) of this mixture were placed into four, 16x100 pyrolyzed glass

test tubes and mixed with 1.5 mL of NaOH (1N) and 1.5 mL chloroform to solubilize the

estrogens. Tubes were vortexed twice for 20 s and centrifuged (2500 x g for 20 min).

The chloroform phases were pooled; 1.0 mL was aliquoted into four test tubes and

mixed with 180 �L of 90% acetic acid, to lower the pH to 4.4, and 3.0 mL toluene. Tubes

were vortexed twice for 20 s and centrifuged (2500 x g for 20 min). Samples were

stored overnight at -20�C to enhance phase separation. The toluene phase was

decanted into clean tubes and stored at -20�C. The toluene extraction was repeated on

the chloroform phase. Toluene phases were combined, evaporated to dryness using N2

gas (Organomation; Berlin, MA) to concentrate the estrogens, and stored at -20�C.

60

Specific gravity of fecal samples was measured (Lupton and Ferrell, 1986) to convert

estrogen content (wt/vol) to excreted quantities.

Urine

Daily urine samples were pooled to one sample per collection period, weighted

by daily excretion (wet basis) for each heifer, then extracted using a base extraction

technique described by Zhao et al. (2009) and outlined above. Specific gravity of urine

samples was measured (Myers and Beede, 2009) to convert estrogen content (wt/vol)

to excreted quantities.

Yeast Estrogen Screen (YES) Bioassay

Extracted feces and urine samples were analyzed for total estrogenicity using the

YES bioassay following the procedure developed by Routledge and Sumpter (1996)

and modified for use in dairy waste (Zhao et al., 2009). In brief, a recombinant yeast

strain (Saccharomyces cerevisiae) containing the human estrogen receptor (hER) gene

and a chromogenic reporter system was used to measure total estrogenic activity,

expressed as 17-β E2 equivalents (E2-eq). In the recombinant strain, the estrogen

response elements are located on an extrachromosomal plasmid and regulate the

expression of a lacZ reporter gene, which produces β-galactosidase when transcription

is activated. When the estrogen receptor element binds with estrogens and estrogen-

like compounds in the sample of interest, amount of estrogenic activity can be quantified

by color change by β-galactosidase (Routledge and Sumpter, 1996).

The assay was carried out in a laminar flow hood (Contamination Control INC;

Lansdale, PA). Evaporated sample extracts were re-suspended with 1.0 mL of absolute

EtOH. In sterile flat-bottomed 96-well microtiter plates (Becton Dickinson Labware;

61

Franklin Lakes, NJ) 100 �L of the re-suspended sample was serially diluted and 10 �L

of each serial dilution was aliquoted in triplicate. Plates were allowed to evaporate to

dryness in air before 200 �L of assay medium containing yeast cells (grown to an

absorbance of 1.0 at 620 nm) and chlorophenol red-β-D-galactopyranoside (CPRG)

were added to each well (Holbrook et al., 2002). The plates were sealed and incubated

at 32�C for 24 hr and then at room temperature for 12 hr. Color density was quantified

by measuring the absorbance at 575 nm and cellular density was quantified at an

absorbance of 620 nm (�Quant BioTek Instruments, INC; Winooski, VT). Duplicates of

each extracted sample were run on the same plate. Each plate also contained a 17-β

E2 standard curve (>98% purity, Sigma Chemical Company; St. Louis, MO) ranging

from 976 to 125000 ng/mL. Daily fecal estrogenic excretion was calculated as the

product of fecal E2-eq concentration and fecal output. Daily urinary estrogenic excretion

was calculated as the product of urinary E2-eq concentration and urinary output.

LC/MS/MS analysis

Feces and urine samples from five heifers throughout the two periods, and

samples of both hays from both periods were analyzed using LC/MS/MS. Feces and

urine samples were pooled as before, freeze-dried (Freezone Plus 6, Labconco;

Kansas City, MO), and ground using mortar and pestle. Hay samples were dried at

55�C for 48 h in a forced air oven and ground with a Wiley mill (1-mm screen; Arthur H.

Thomas; Philidephia, Pa). Triplicate aliquots (0.5 g) of sample were mixed with

hydramatrix (Varian, Inc; Palo Alto, CA) using mortar and pestle until the mixture was

uniform. Samples were extracted in amber bottles using 50:50 (vol/vol) isopropyl

alcohol/water (10 mL), vortexed, heated (45�C for 1 h), rotated (1 h), vortexed again,

62

and centrifuged (150 rpm for 10 minutes). The supernatant was decanted into a clean

amber bottle and refrigerated overnight. The extraction was repeated, after which the

supernatants were combined and evaporated to half the original volume with N2 gas.

500 �L of the extract was transferred to vials (Agilent Technologies, Inc.; Santa Clara,

CA) and stored until analysis. Samples were spiked according to a standard spiking

procedure.

A liquid chromatograph (Agilent Technologies, Inc.; Santa Clara, CA) coupled to

a Micromass Quatro Micro triple-quadrupole mass spectrometer (LC/MS/MS) (Waters

Inc.; Milford, MA) was used for quantitative analysis of selected phytoestrogens:

genistein, daidzein, equol, formononetin, coumestrol, biochanin A, and 2-carbethoxy-

5,7-dihydroxy-4'-methoxyisoflavone. These phytoestrogens were selected for analysis

based on reported presence in red clover hay and other feedstuffs. Two mobile phases

were used (mobile phase A consisted of distilled/deionized water, while mobile phase B

consisted of methanol) at a flow rate of 0.4 mL/min through the Waters Atlantis dC18

3�m, 30 x 150 mm column (Waters Inc.: Milford, MA). An isocratic pump was used after

the liquid chromatography column with 10 mM ammonium hydroxide as a mobile phase

flowing at a rate of 0.1 mL/min. MassLynx (Waters Inc.; Milford, MA) was used as the

data acquisition interface.

Statistical Analysis

Estrogenic activity and excretion of E2-eq in feces and urine

Concentrations and excretion of E2-eq in feces and urine were analyzed using

the Mixed procedure of SAS (9.1, 2003) with the model:

Yij = � + Hi + Pj + Dk + eijk

63

where:

� = observed mean;

Hi = effect of heifer (i = 1 to 10);

Pj = effect of period (d= 1 to 2);

Dk = effect of diet (k= red clover, grass); and

eij = error (interaction of heifer and diet)

Data were reported as least squares means (LSM) � SE. Significance was

declared at P < 0.05 and trends at P < 0.10.

Concentrations of phytoestrogens in feces and urine

Concentrations of phytoestrogens in feces and urine were analyzed using the

Mixed procedure of SAS (9.1, 2003) with the same model as above with one

modification:

Hi = effect of heifer (i = 1, 2, 3, 4, 5)

Data were reported as LSM � SE. Significance was declared at P < 0.05 and

trends at P < 0.10.

RESULTS AND DISCUSSION

Effect of diet on estrogenic activity of feces and urine

DMI significantly increased with feeding of grass hay (P <0.01; Table 4.2).

Feeding of grass hay significantly increased DM digestibility (P = 0.04; Table 4.2).

Feeding red clover significantly increased urinary output when compared to grass hay

(P < 0.01; Table 4.2). The effect of diet on urine output was likely due to higher protein

content of red clover diets (13.7 vs 12.6%). The increase in urine output here (3.1 kg/d

64

with 0.9 unit increase in dietary protein) is somewhat greater than the increases of 1.0

to 1.9 L/d per percentage unit increase in dietary protein observed by Dinn et al. (1998)

and Leonardi et al. (2003). Furthermore, increased concentrations of Na and K increase

urine output because of the kidney’s regulation of urinary excretion of these to maintain

electrolyte homeostasis. (Berliner et al., 1950; Pickering, 1965). Concentrations of Na

and K were higher in the red clover hay (0.08% of DM and 1.0% of DM) than in the

grass hay (0.06% of DM and 0.81% of DM). Fecal output was not significantly affected

by diet (P < 0.7; Table 4.2).

Feeding red clover hay significantly increased both urinary E2-eq concentrations

(P = 0.01; Table 4.3) and daily urinary excretion of estrogenic equivalents (P = 0.01;

Table 4.3) when compared to grass hay. Similarly, feces from heifers fed red clover hay

tended to have greater E2-eq concentrations (P = 0.06; Table 4.3) and fecal excretion of

estrogenic equivalents (P = 0.08; Table 4.3).

Limited data is available on the effect of dietary inclusion of red clover on

estrogen excretion in feces and urine and no data is available on the effect of diet on

E2-eq excretion. Shutt et al. (1970) observed total phytoestrogen excretion in urine of

3820 mg/d for sheep fed red clover hay, while sheep fed subterranean clover (a less

estrogenic legume) excreted 56 mg/d of total phytoestrogens in urine. Total

phytoestrogen excretion in feces equaled 250 mg/d for sheep fed red clover hay, as

compared to 11 mg/d for sheep fed subterranean clover (Shutt et al., 1970).

Furthermore, substantial metabolism of specific phytoestrogens was observed.

Formononetin was converted to equol in the rumen by the microbial population; this

65

conversion to equol resulted in high concentrations of equol in urine and the feces

despite the lack of detectable equol in the diet (Shutt et al., 1970).

In the current study, intake of genistein, daidzein, and formononetin significantly

increased with feeding of red clover hay while intake of biochanin A was higher in

heifers fed grass hay (Table 4.5). Concentrations of daidzein and formononetin in feces

tended to increase with feeding of red clover hay (P = 0.07; Table 4.4); daily fecal

excretion of these two and of genistein significantly increased with feeding of red clover

(Table 4.5). The concentration of equol and coumestrol in feces significantly increased

with feeding of red clover although it was not detected in the diet (Table 4.4). Biochanin

A and 2-carbethoxy-5,7-dihydroxy-4'-methoxyisoflavone were detected in feces but

neither concentration nor excretion of these via feces were affected by diet (Table 4.4).

Daidzein, equol, formononetin, and 2-carbethoxy-5,7-dihydroxy-4'-methoxyisoflavone

were detected in urine but urinary concentrations and excretion of these were not

affected by diet (Table 4.4, Table 4.5). Quantitative comparison of total excretion of

specific compounds to intake of each compound suggests that equol and daidzein were

produced at the expense of the other four measured compounds.

Thangavelu et al. (2008) observed increased excretion of three phytoestrogens

(secoisolariciresinol diglycoside (SDG) and its metabolites, enterolactone and

enterodiol) by cows with increased dietary inclusion of phytoestrogens. Quantification of

the phytoestrogens was via GC-MS. Inclusion of flaxseed (10% of DM), a rich source of

SDG, resulted in increases in fecal and urinary concentrations of SDG in cows. Fecal

SDG concentrations averaged 34.7 �g/g for the flaxseed diet (P < 0.01), but did not

increase SDG concentrations in urine. In humans and rats, dietary flaxseed increases

66

concentrations of all three compounds in feces and urine (Wang, 2002), but the

complexity and difference in digestive physiology of ruminants make metabolic

pathways of these phytoestrogens vastly different than those in monogastrics

(Thangavelu et al., 2008).

Steinshamn et al. (2008) observed higher milk concentrations of biochanin A,

equol, and formononetin in cows fed red clover silage than those fed white clover silage;

the change in equol was most sizeable. Steinshamn et al. (2008) highlighted the lack of

understanding of the mechanism of phytoestrogen recovery from feed.

There was a tendency for the effect of period to be significant in fecal E2-eq

concentrations (P = 0.06; Figure 4.1) and fecal excretion of estrogenic equivalents (P =

0.08; Table 4.3) occurred in the second period. Fecal equol concentrations tended to

increase in the first period (Effect of period P < 0.08; Figure 4.1). The biological

explanation for these is not apparent but undetected variation in the estrogenic activity.

Period did not affect urinary concentrations of any of the compounds or estrogenic

activity of urine.

Differences in quantification by YES bioassay and LC/MS/MS

Observed changes in content of specific phytoestrogens were reflected in

changes in total estrogenic activity of feces and urine samples. The YES bioassay

produced E2-eq concentrations lower than the sum of the phytoestrogen concentrations

quantified by LC/MS/MS (data not shown). This disparity may result from low binding

affinities of the phytoestrogenic compounds in the samples to the mammalian

expression vector used in the YES bioassay. Kuiper et al. (1998) determined relative

binding affinities of several phytoestrogens relative to 17-β E2. Compounds with the

67

highest relative binding affinity were coumestrol (73.5%) and genistein (26.2%).

Daidzein, formononetin, and biochanin A had binding affinities less than 1%. These

values are slightly higher than the relative binding affinities quantified by Shutt and Cox

(1972) using cytosol of sheep uteri as the indicator: coumestrol (5%), genistein (0.9%),

daidzein (0.1%), and equol (0.4%) The relatively low binding affinity of phytoestrogen to

the estrogen receptor explains the difference in magnitude of estrogenic activity

quantification by the YES bioassay.

Also estrogenic activity may be underestimated by the YES bioassay due to the

presence of chemicals in the sample that are toxic or antagonistic to the yeast cells

(Nakada et al., 2005). Nakada et al. (2004) observed that estrogenicity estimated by the

YES bioassay was two- to ten-fold less than estrogenicity estimated by GC-MS

analysis. They concluded fractionation occurring in the column chromatography

separated any antagonistic or interfering chemicals from the estrogenic chemicals

allowing for more accurate quantification (Nakada et al., 2005).

CONCLUSIONS

Feeding red clover to dairy heifers increases the estrogenic activity of feces and

urine. The increase in dietary phytoestrogens resulted in increased excretion of five of

seven measured phytoestrogens in the feces. The low recovery of phytoestrogens in

the urine and feces while feeding red clover suggests that phytoestrogens are

metabolized to other compounds in the digestive tract. The increased excretion of

estrogenic equivalents in feces and urine of heifers fed red clover suggests that these

metabolites retain estrogenic activity. Diet needs to be considered when instituting best

management practices for control of estrogen losses from farms.

68

ACKNOWLEDGEMENTS

The authors would like to thank the Organic Geochemistry Research Group at

the USGS in Lawrence, KS for assistance with LC/MS/MS method development for

phytoestrogen detection. The work of Shane Brannock, Curtis Caldwell, Rachael Dunn,

Dana Gochenour, Karen Hall, Ashley Jones, Katharine Pike, Partha Pratim Ray, William

Saville, and Abigail Schmidt during sample collection and analysis is greatly

appreciated.

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lactating dairy cows fed diets supplemented with hydrogenated animal fat, flaxseed

or sunflower seed. J. Reprod. Dev. 54:439-446.

Wang, L.-Q. 2002. Mammalian phytoestrogens: enterodiol and enterolactone. J.

Chromatogr. B, Biomed Appl.777:289-309.

70

Zhao, Z., Y. Fang, N. G. Love, and K. F. Knowlton. 2009. Biochemical and biological

assays of endocrine disrupting compounds in various manure matrices.

Chemosphere 74:551-555.

71

Item

Red clover diet2

Grass diet2

Ingredients1

Red Clover Hay

84.7

--

Grass Hay

--

84.2

Wheat midds

8.21

8.21

Soybean hulls

3.48

3.48

Corn gluten feed

1.53

1.53

Dried distillers grain

0.77

0.77

Molasses

0.46

0.46

Limestone

0.33

0.33

Corn, dried and ground

0.19

0.19

Soybean meal, high protein

0.19

0.19

Vitamin and Mineral Mix3

0.151

0.151

Nutrient Composition

CP

13.7

12.6

NDF

47.6

67.6

Ca

0.28

0.16

K

1.0

0.81

Mg

0.06

0.09

Na

0.08

0.06

P

0.33

0.27

1 All ingredients except red clover and grass were provided as part of a pelleted

supplement.

2 % of DM

3 Contained: 64.9% Salt, 13.26% Potassium/Magnesium sulfate, 7.28% Selenium, 5.30%

Phosphate dicalcium, 160,000 mg/kg Zn, 150,000 mg/kg Mn, 4,000 mg/kg Cu, 3,500

mg/kg I, 1,600 mg/kg Co, 26,400 kIU/kg vitamin A, 8,800 kIU/kg vitamin D, and 4,400

kIU/kg vitamin E.

Table 4.1 Ingredient composition of diet.

72

Table 4.2 Effect of diet on DMI, DM digestibility, and excreta output.

Red Clover Diet

Grass Diet

SEM1

P-value

DMI (kg/d)

7.7

8.8

0.3

0.0089

DM digestibility (%)

58.3

62.6

1.0

0.04

Feces (kg/d)

22.1

21.5

0.8

0.67

Urine (kg/d)

11.9

8.8

0.6

0.0006

1SEM = Standard error of the mean

73

Table 4.3 Effect of diet on estrogenic activity and excretion of estrogenic

equivalents in feces and urine.

Red Clover Diet Grass Diet SEM1 P-value

Fecal E2-eq (�g/mL)

3.92

2.64

0.4

0.06

Fecal E2-eq (mg/d)

84.4

57.4

8.6

0.08

Urine E2-eq (�g/mL)

9.89

3.78

1.6

0.01

Urine E2-eq (mg/d)

120.2

35.6

20

0.01

1SEM = standard error of the mean

74

Table 4.4 Effect of diet on excretion of phytoestrogenic compounds in excreta as

determined by LC/MS/MS.

Red Clover Diet Grass Diet

SEM

P-value

-----------------�g/g---------------

Biochanin A

Fecal excretion

0.27

0.20

0.06

0.55

Urinary excretion

ND1

ND

--

--

Coumestrol

Fecal excretion

1.30

0.59

0.18

0.27

Urinary excretion

ND

ND

--

--

Daidzein

Fecal excretion

4.56

2.14

0.58

0.07

Urinary excretion

0.06

0.06

0.01

0.75

Equol

Fecal excretion

76.6

16.6

10.4

0.004

Urinary excretion

4.33

4.07

0.52

0.83

Formononetin

Fecal excretion

8.28

1.0

1.7

0.07

Urinary excretion

0.12

0.09

0.01

0.21

Genistein

Fecal excretion

1.41

0.33

0.21

--

Urinary excretion

ND

ND

--

--

2-carbethoxy-5,7-dihydroxy-

4'-methoxyisoflavone

Fecal excretion

0.07

0.01

0.03

0.52

Urinary excretion

0.61

0.29

0.19

0.52

1ND = not detectable

75

Table 4.5 Effect of diet on phytoestrogenic compounds in feed and excreta as

determined by LC/MS/MS.

Red Clover Diet Grass Diet

SEM

P-value

-----------------mg/d---------------

Biochanin A

Intake

31.8

77.8

12.9

0.004

Fecal excretion

5.7

3.7

1.0

0.25

Urinary excretion

ND1

ND

--

--

Coumestrol

Intake

ND

ND

--

--

Fecal excretion

27.8

8.8

5.22

0.03

Urinary excretion

ND

ND

--

--

Daidzein

Intake

158.1

34.2

21.9

0.002

Fecal excretion

96.3

46.2

12.8

0.04

Urinary excretion

1.3

1.3

0.3

0.85

Equol

Intake

ND

ND

--

--

Fecal excretion

1634.0

340.3

233

0.006

Urinary excretion

49.7

34.9

7.3

0.27

Formononetin

Intake

940.5

226.0

132

0.002

Fecal excretion

162.8

18.3

29.0

0.03

Urinary excretion

2.6

1.9

0.3

0.28

Genistein

Intake

158.3

26.2

22.6

0.001

Fecal excretion

29.9

3.0

4.8

0.001

Urinary excretion

ND

ND

--

--

2-carbethoxy-5,7-dihydroxy-

4'-methoxyisoflavone

Intake

ND

ND

--

--

Fecal excretion

1.4

0.3

0.63

0.27

Urinary excretion

5.9

2.3

1.7

0.36

1ND = not detectable

76

0

10

20

30

40

50

60

0

10

20

30

40

50

60

Fecal E2-eq

Fecal Equol

F

e

ca

l E

q

u

o

l (�

g

/g

)

F

e

ca

l E

2

-e

q

(�

g

/m

L

)

Period 1

Period 2

Figure 4.1 Effect of period on fecal estrogenic activity. Data are reported as

LSM � SE. Period effect was significant for fecal E2-eq (�g/mL). Period effect

had a tendency to be significant for fecal equol (�g/g) (P < 0.08).

77

Appendix A

PROTOCOL FOR 125IODINE ESTRADIOL RADIOIMMUNOASSAY

I. Stock solutions

A. Buffers

1. 0.2M Monobasic Sodium Phosphate: Dissolve 2.76 g NaH2PO4�H2O in H2O

and dilute to 100 mL.

2. 0.2M Dibasic Sodium Phosphate: Dissolve 2.84 g Na2HPO4 in H2O and

dilute to 100 mL.

3. 0.01M Phosphate buffered saline with gelatin (PBS-gel)

1 liter

pH=7.2

250 mL

9 g

NaCl

2.25 g

1 g

Gelatin

250 mg

1 g

Sodium Azide

250 mg

14 mL

.2M NaH

2

PO4

3.5 mL

36 mL

.2M Na

2

HPO

4

9 mL

9.16 mg

Phenol Red

2.29 mg

Add components to appropriate size beaker, dilute with slightly less than

total volume of H

2

O, adjust pH to 7.2, quantitatively transfer to appropriate

size volumetric flask (i.e., rinse into flask with H

2

O) and bring up to final

78

volume with H

2

O.

4. Phosphate buffered saline with gelatin and bovine serum albumin (PBS-

bsa). Weigh out 100 mg BSA (Sigma #A7030). Add a small amount of

PBS-gel (just enough to wet the powder) and mash with a glass stirring rod

to attain dissolution. Dilute to 100 mL with PBS-gel.

B. Standards (all standards should be stored at -20�C)

1. Stock A (100 �g/mL) - dissolve 10 mg E2 in EtOH and dilute to 100 mL

with EtOH.

2. Stock B (1 �g/mL) - dilute 1.0 ml Stock A to 100 mL with EtOH.

3. Stock C (100 ng/mL) - dilute 10.0 ml Stock B to 100 mL with EtOH.

4. Stock D (4000 pg/mL) - dilute 4.0 ml Stock C to 100 mL with EtOH.

C. Antiserum: Diagnostic Systems Laboratories Estradiol antibody (from Ultra-

Sensitive Estradiol RIA kit, DSL-4800)

D.125I – E2 Diagnostic Systems Laboratories 125I-Estradiol (from Ultra-Sensitive

Estradiol RIA kit, DSL-4800)

E. Precipitating solution: Diagnostic Systems Laboratories Precipitating Reagent

(from Ultra-Sensitive Estradiol RIA kit, DSL-4800)

F. Ether: Fisher Ethyl Ether Anhydrous #E138-4

III. Label tubes

A. Standards

1. One set of 12x75 glass tubes labeled: 1.5625, 3.125, 6.25, 12.5, 25, 50,

100, 200, 400

79

2. Two sets of 12x75 glass tubes labeled: T, 0, N, .15625, .3125, .625, 1.25,

2.5, 5, 10, 20, 40

Note: These values are pg/tube. Below 1.25 is often not measurable.

B. Samples

1. One set 13x100 glass tubes labeled 12 - 69

2. Two sets of 12x75 glass tubes labeled 12 - 69

IV. Working standards

Note: The following procedure will make enough standards for two assays. The

volumes may be adjusted proportionately for more assays.

A. Pipette 100 �L Stock D (4000 pg/mL) into 12x75 tube labeled 400. Dry down

under air.

B. Reconstitute with 1000 �L EtOH. Cover with parafilm and let sit for at least 1

h with periodic gentle vortexing.

C. Pipette 500 �L EtOH into 12x75 tubes labeled 1.5625, 3.125, 6.25, 12.5, 25,

50, 100 and 200.

D. Transfer 500 �L from the 400 tube to the 200 tube. Mix well. Repeat this

process from the 200 tube to the 100 tube, the 100 tube to the 50 tube, etc. to

finish the serial dilutions.

E. Pipette 100 �L aliquots from each tube into the two remaining sets of 12x 75

tubes (i. e. 100 �L of 400 into 40 etc.). Dry down under air. The T, N and 0

tubes get nothing at this point.

80

F. Reconstitute ALL tubes with 100 �L PBS-gel. Vortex well. Cover with plastic

wrap and store at 4� C overnight.

V. Extraction

A. Set up Hamilton Digital Diluter for 3 mL ether and 500 �L sample

1. Ether - 5 mL syringe at 60%

2. Sample - 1 mL syringe at 50%

B. Dispense 3 mL ether only into first two 13x100 tubes (these are used to test

for an ether blank effect)

C. Dispense ether and Low E2 pool into next two tubes.

D. Dispense ether and High E2 pool into next two tubes.

E. Dispense ether and samples into remaining tubes.

F. Cover with plastic wrap and vortex 2 minutes on the rack vortexer.

G. Freeze in dry ice alcohol bath (do NOT put in ultra-low freezer).

H. Pour off ether into one set of 12x75 tubes.

I. Dry down under gentle stream of air.

J. Re-extract with 3 mL ether; vortex 2 minutes; freeze; pour ether into same

12x75 tubes; dry under air.

K. Rinse sides of tubes with 0.5 mL ether and dry down.

L. Reconstitute all tubes with 100 �L PBS-bsa. Vortex well. Cover with plastic

wrap and store at 4� C overnight.

VI. Assay

A. Reconstituted extracts from step K above were assayed directly

81

B. Combine standard and sample tubes into one rack.

C. Add 30 �L E2 antibody to all tubes except T and N. Add 30�L PBS-gel to N

tubes. Vortex. Incubate at room temperature for 1 h.

D. Add 50 �L

125

I-E2 to ALL tubes. Vortex. Incubate at room temperature for 2 h.

E. Remove T tubes from rack and set aside. Add 1 mL precipitating solution to

ALL remaining tubes. Vortex. Incubate in centrifuge at 4� C for 20 minutes.

F. Centrifuge at 2500g for 20 minutes at 4� C.

G. Decant supernatant to waste container and allow tubes to drain inverted on

absorbent paper for 15 minutes. Gently blot the last drop onto dry absorbent

paper.

H. Count tubes for 1 minute.

82

Appendix B

PROTOCOL FOR YEAST ESTROGEN SCREEN (YES) BIOASSAY

Preparation and storage of minimal media and medium components

Minimal medium and medium components prepared in glassware contaminated

with an oestrogenic chemical will lead to elevated background expression. Glassware,

spatulas, stirring bars, etc., must be scrupulously cleaned, and should not have had

prior contact with steroids. Rinse glassware, spatulas, stirring bars twice with absolute

ethanol, and leave to dry. Alternatively, wash twice with methanol, and once with

ethanol.

Minimal Medium (pH 7.1)

Add 13.61 g KH2PO4, 1.98 g (NH4) 2SO4, 4.2 g KOH pellets, 0.2 g MgSO4, 1 mL

Fe2(SO4)3 solution (40 mg/50 ml H2O), 50 mg L-leucine, 50 mg L-histidine, 50 mg

adenine, 20 mg L-arginine-HCl, 20 mg L-methionine, 30 mg L-tyrosine, 30 mg L-

isoleucine, 30 mg L-lysine-HCl, 25 mg L-phenylalanine, 100 mg L-glutamic acid, 150 mg

L-valine, and 375 mg L-serine to 1 L double-distilled water. Place on heated stirrer to

dissolve. Sterilize at 121�C for 10 min, and store at room temperature.

D-(+)-Glucose

Prepare a 20% w/v solution. Sterilize in 50 mL aliquots at 121�C for 10 min. Store

at room temperature.

L-Aspartic Acid

Make a stock solution of 4 mg/mL. Sterilize in 50 mL aliquots at 121�C for 10

min. Store at room temperature.

Vitamin Solution

83

Add 8 mg thiamine, 8 mg pyridoxine, 8 mg pantothenic acid, 40 mg inositol, and

20 mL biotin solution (2 mg/100 mL H2O) to 180 mL double-distilled water. Sterilize by

filtering through a 0.2-μm pore size disposable filter, in a laminar air flow cabinet. Filter

into sterile glass bottles in 10 mL aliquots. Store at 4�C.

L- Threonine

Prepare a solution of 24 mg/mL. Sterilize in 10 mL aliquots at 121�C for 10 min.

Store at 4�C.

Copper (II) Sulfate

Prepare a 20 mM solution. Sterilize by filtering through a 0.2-μm pore size filter,

in a laminar flow cabinet. Filter into sterile glass bottles in 50 mL aliquots. Store at room

temperature.

Chlorophenol red-β-D-galactopyranoside (CPRG)

Make a 10 mg/mL stock solution. Sterilize by filtering through a 0.2-μm pore size

filter into sterile glass bottles, in a laminar flow cabinet. Store at 4�C.

Preparation and storage of yeast stock

Carry out all yeast work in a type II laminar flow cabinet.

Short term storage of yeast

Day 1

Prepare growth medium agar plate by adding 1 g of Difco agar to 90 mL minimal

media. Autoclave the mixture and temper it. Add 10 mL glucose solution, 2.5 mL L-

aspartic acid solution, 1.0 mL vitamin solution, 0.8 mL L-threonine solution, and 250 �L

copper (II) sulfate solution. Pour agar mixture into 4 sterile plates. Allow plates to set

84

and place in 32�C incubator for 24 hours.

Day 2

Obtain small amount of yeast from long term storage stock. Place one drop onto

each of the four agar plates. Streak plates for isolation. Allow plates to dry slightly,

invert, and place in 32�C incubator. Once single colonies grow place plates in

refrigerator for one month.

Long term storage of yeast

Day 1

Prepare growth medium by combinig 45 mL minimal media, 5 mL glucose

solution, 1.25 mL L-aspartic acid solution, 0.5 mL vitamin solution, 0.4 mL L-threonine

solution, and 125 �L copper (II) sulfate solution. Obtain one colony from short term

storage agar plates and inoculate the growth media with it. Place media in 32�C

incubator until it reaches an absorbance of 1 (620nm).

Day 2

Transfer the culture to a sterile 50 mL conical tube. Centrifuge the conical tube

for 10 minutes (4�C at 2,000 x g). Decant the supernatant and resuspend the culture in

5 mL minimal media with 15% glycerol. Transfer 0.5 mL aliquots into cryovials, label,

and freeze at -80�C.

85

Assay procedure

Carry out all yeast work in a type n laminar flow cabinet.

Day 1

Prepare growth medium by adding 5 mL glucose solution, 1.25 mL L-aspartic

acid solution, 0.5 mL vitamin solution, 0.4 mL L-threonine solution, and 125 �L copper

(II) sulfate solution to 45 mL minimal medium. Add 1 colony from short term storage

agar plate. Incubate at 32�C until it reaches an absorbance of 1 (620 nm).

Day 2

Serially dilute re-suspended samples and standard in 100 �L absolute ethanol in

a 96-well microtitre plate. Transfer 3 - 10 �L aliquots of each concentration to a 96-well

microtitre plate. Add 10 �L absolute ethanol (or appropriate solvent) to blank wells.

Leave chemicals in the assay plate to evaporate to dryness.

Prepare growth medium by adding 5 mL glucose solution, 1.25 mL L-aspartic

acid solution, 0.5 mL vitamin solution, 0.5 mL CPRG, 0.5 mL of yeast, 0.4 mL L-

threonine solution, and 125 �L copper (II) sulfate solution to 45 mL minimal medium.

Add 200 μl of the seeded assay medium to wells using a multi-channel pipette. Each

assay should contain a plate with one row of blanks (solvent and assay medium only)

and two rows of abiotics (assay medium without yeast added). Finally, each assay

should have a 17β - estradiol standard curve. Seal the plates with autoclave tape and

shake vigorously for 2 min. Incubate at 32�C for 24 hours.

Day 3

Shake the plates vigorously for 2 min, to mix and disperse the growing cells.

Place on bench top to develop further for 12 hours. Read the plates at an absorbance of

86

575 nm and 620 nm suing a plate reader.

Calculations

To correct for turbidity the following equation needs to be applied to the data:

Corrected value = chem. abs. (540 nm) - [chem. abs. (620 nm)-blank abs. (620 nm)]

87

Appendix C

PROTOCOL FOR LC/MS/MS ANLAYSIS OF PHYTOESTROGENS

Extraction Procedure for Phytoestrogen Samples

1. Weigh out 3 0.5 grams of sample into labeled aluminum pans.

a.

1 = Unspiked

b.

2 = Before Spike

c.

3 = After Spike

2. To each sample add 0.5 hydramatrix and combine sample and hydramatrix using

mortar and pestle until it is a uniform mixture.

3. Transfer samples to labeled 40mL amber bottles with septa.

4. Follow the spiking procedures to spike the unspiked, before spike, and after spikes.

5. Add 10mL of 50:50 (v/v) Isoprpyl Alcohol / Water to each sample. This is vial 1.

6. Vortex samples, and heat all samples at 45�C for one hour.

7. While samples are heating obtain a second set of labeled 40mL amber bottles with

septa and record weights as vial 2.

8. Vortex samples, rotate them for one hour, and vortex again.

9. Centrifuge samples at 1.5 rpm x 100 for 10 minutes.

10. Pour the top layer of the centrifuged samples into vial 2.

11. Add 10mL of 50:50 (v/v) Isoprpyl Alcohol / Water to each sample in vial 1.

12. Vortex samples, and heat all samples at 45�C for one hour.

13. Vortex samples, rotate samples for one hour, and vortex samples.

14. Centrifuge samples at 1.5 rpm x 100 for 10 minutes.

15. Pour the top layer of the centrifuged samples into vial 2.

88

16. Follow the spiking procedures to spike the unspiked, before spike, and after spikes.

17. Weigh vial 2 and record.

18. Using nitrogen gas, blow each sample down to half the original weight of the extract.

19. Weigh each sample extract and determine which is the heaviest.

20. To each sample add enough water so that the weight of the extract equals that of

the heaviest extract. Record the amount of water added and the final weight.

21. Transfer 500�L of each sample into labeled clear Agilent vials and place in freezer

until ready to run.

Spiking Procedure for Phytoestrogen Samples

Before addition of the 10mL 50:50 (v/v) Isoprpyl Alcohol / Water:

To ALL Samples:

Add 100�L of the 1ng/�L LCHM surrogate standard

Add 200�L of the 1ng/�L LCPE d4-Genistein standard.

To the BEFORE SPIKE Samples:

Add 200�L of the 1ng/�L LCHM Analyte Standard Mix

Add 200�L of the 1ng/�L LCPE Analyte Standard Mix

After combining the two extracts:

To ALL Samples:

Add 100�L of the 1ng/�L LCHM Internal Standard

To the AFTER SPIKE Samples:

Add 200�L of the 1ng/�L LCHM Analyte Standard Mix

Add 200�L of the 1ng/�L LCPE Analyte Standard Mix