the effects of dietary clover species on reproduction in the ewe lacey beam department of animal...
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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