THE EFFECTS OF DIETARY CLOVER SPECIES ON

REPRODUCTION IN THE EWE

LACEY BEAM

DEPARTMENT OF ANIMAL SCIENCES

OREGON STATE UNIVERSITY

BACKGROUND

Escalon, CA

BACKGROUND

• SAN JOAQUIN DELTA COLLEGE2000-2002

• OREGON STATE UNIVERSITY– B.S. IN ANIMAL

SCIENCE 2004

• OREGON STATE UNIVERSITY– M.Ag. GRADUATE

STUDENT

REPRODUCTION

• REPRODUCTIVE DIFFICULTIES IN SHEEP GRAZING CLOVER SPECIES WERE FIRST RECOGNIZED IN 1946 (Bennetts et al.)

• “CLOVER DISEASE”– SYNDROME OF ABNORMAL

REPRODUCTIVE FUNCTIONS OF EWES GRAZING CLOVER PASTURES

GRAZING

• LEGUMES ARE A WIDELY AVAILABLE FEEDSTUFF FOR MAINTAINING RUMINANT ANIMALS

• SHEEP ARE A USEFUL TOOL IN A GRAZING SYSTEM– SEED TO SOIL CONTACT– CREATES MORE TILLARS– CONTROLS PLANT SIZE– INEXPENSIVE FERTILIZER– LEGUMES ARE HIGH IN CP,

DIGESTIBILITY, INTAKE

CLOVER SPECIES

• SUBTERRANEAN CLOVER Trifolium subterraneum

Cultivars Formononetin % DM

Yarloop 1.5

Dwalganup 1.3

Dinninup 1.2

Geraldton .9

Tallarook .8

Daliak .2

Clare .15

Trikkala .15

Seaton Park .12

Bacchus Marsh .11

CLOVER SPECIES

• RED CLOVER Trifolium pratense

Cultivars Formononetin % DM

Broad .99

Tetraploid .90

Morocco .14

PHYTOESTROGENS

• DEFINITION: COMPOUND THAT EXERTS ESTROGENIC EFFECTS ON THE CNS, INDUCE ESTRUS, AND STIMULATE GROWTH OF THE GENITAL TRACT OF FEMALE ANIMALS

• CONTAINED IN MANY LEGUMES

• ESTROGENIC ACTIVITY DEPENDS ON POSITION OF 2 HYDROXYL GROUPS

PHYTOESTROGENS

• PHYTOESTROGEN CONTENT VARIES BETWEEN PLANT SPECIES, AND GROWING AND HARVESTING CONDITIONS

– EARLY SPRING:• PLANT STRESS DUE TO CHANGES IN AVAILABLE

NITROGEN OR PHOSPHORUS • TEMPERATURE

– DISEASE

– DROUGHT

– INCREASES PHYTOESTROGEN ACCUMULATION IN LEAVES

PHYTOESTROGENS

• PHYTOESTROGENS CONTAIN ESTROGENIC COMPOUNDS:

COUMESTANS

ISOFLAVONES

LIGNANS

PHYTOESTROGENS

COUMESTANS

• COUMESTROL– MOST COMMON

COUMESTAN– MOST ESTROGENIC

POTENCY OF ALL

PHYTOESTROGENS(ADAMS, 1995a)

PHYTOESTROGENS

ISOFLAVONES

• FORMONONETIN – MOST IMPORTANT

ISOFLAVONE PERTAINING TO RUMINANTS

– REDUCED AND DEMETHYLATED INTO THE MORE ESTRTOGENIC COMPOUND EQUOL

(Lundh, 1990)

EQUOL

• MORE ESTROGENIC THAN FORMONONETIN

• RAPIDLY ABSORBED THROUGH RUMINAL WALL

• MAJOR ESTROGENIC METABOLITE THAT INITIATES ESTROGENIC EFFECTS IN SHEEP

• CHEMICAL STRUCTURE RESEMBLES ESTRADIOL - ALLOWS BINDING TO THE ESTROGEN RECEPTOR

Equol Estradiol(Lundh, 1990) (ADAMS, 1995a)

RUMINANTS AND ISOFLAVONES

• DEGREDATION AND DETOXIFICATION OF ISOFLAVONES TAKES PLACE IN THE RUMEN

• RESULTING IN ESTROGENIC RUMEN CONTENTS

• RUMEN MICROBES BREAKDOWN ALL OTHER ISOFLAVONES INTO THEIR NONESTROGENIC METABOLITES

• FORMONONETIN EQUOL

EFFECTS ON SHEEP

• EWE INFERTILITY

TEMPORARY:• DECREASED FIRST SERVICE CONCEPTION

• IRREGULAR ESTRUS– DECREASED OVARIAN WEIGHTS– EXCESSIVE SMALL AND MEDIUM FOLLICLES

DEFICIENT OF ANTRUM FORMATION, EARLY ATRESIA

• REDUCED OVULATION AND CONCEPTION RATES– REDUCED LAMBING RATES AND MULTIPLE BIRTHS

EFFECTS ON SHEEP

PERMANENT:• REPEATED GRAZING:

– DECREASES RESPONSIVENESS TO ESTROGEN

– BARRENNESS

• CERVIX- SERVES AS A RESERVOIR FOR SPERM DURING INSEMINATION AND OVULATION

EFFECTS ON SHEEP

• PROLONGED EXPOSURE TO ESTROGEN LEADS TO DEFEMINIZATION OF CERVIX– BECOMES SHORTER

AND BROADER– INAPPROPRIATE MUCUS

VISCOSITY UNABLE SPERM

TO MIGRATE THROUGH CERVIX – LOSS OF ABILITY TO STORE

SPERMATOZOA

MEASUREMENTS OF ESTROGENIC FEEDS

• UDDER DEVELOPMENT AND MILK SECRETION IN UNBRED EWES

• WETHERS MAY ALSO SECRETE MILK

• INCREASED TEAT LENGTH– DIRECTLY CORRELATED TO

CONCENTRATIONS OF FORMONONETIN IN PASTURE

ADDITIONAL PROBLEMS

• DYSTOCIA

• UTERINE PROLAPSE

• ABORTIONS

• NEONATAL MORTALITY

RESEARCH

• RESEARCH PAPER

• AREAS OF INTEREST– SUBTERRANEAN CLOVER CAN ACCUMULATE UP

TO 5% WEIGHT OF ISOFLAVONES– ISOFLAVONES ARE ONLY PRESENT IN GREEN

CLOVER (ADAMS, 1995a)

– RAPIDLY DRIED HAY MAY RETAIN ISOFLAVONE CONCENTRATIONS

RESEARCH

• OBJECTIVES– TO DEFINE RAPIDLY DRIED HAY VS. SLOWLY

DRIED HAY– TO DETERMINE THE DIFFERENCES IN

ISOFLAVONE LEVELS BETWEEN RAPIDLY AND SLOWLY DRIED CLOVER HAY

– TO DETERMINE IF CUTTING AND HARVESTING CLOVER FOR EWE FEED HAS A NEGATIVE IMPACT ON REPRODUCTION

RESEARCH

• HYPOTHESIS– FEEDING SLOWLY DRIED CLOVER HAY

TO EWES WILL HAVE LOWER CONCENTRATIONS OF ISOFLAVONES AND LESS NEGATIVE REPRODUCTIVE EFFECTS THAN THE SAME GRAZED CULTIVAR

EXPECTED OUTCOMES

• SLOWLY DRIED CLOVER HAY WILL CONTAIN LOWER LEVELS OF ISOFLAVONES THAN RAPIDLY DRIED CLOVER HAY

• NEGATIVE REPRODUCTIVE EFFECTS ON THE EWE SHOULD BE REDUCED COMPARED TO GRAZED GREEN CLOVER

• SPECIFIC EVENTS DURING THE DRYING PROCESS THAT REDUCES/ELIMINATE ISOFLAVONE CONCENTRATIONS

QUESTIONS?

THANK YOU