Exam 2 - Equine Reproduction Flashcards
mare estrous cycle
21 days
mares seasonal or non-seasonal breeders
seasonally polyestrous
long day breeders
april-oct
mare gestation
340 days
mare placenta
diffuse chorionic, epitheliochorial
what are the 4 seasons of ovarian function in a mare
winter anestrus
spring transition
physiologic breeding season
fall transition
what is the mechanism of photoperiods with seasonal reproduction in the horse
increase day length
decrease melatonin
increase GnRH
increase FSH/LH
what is the spring transition period
2-3months
follicular development until one dominant follicle ovulates
prolonged/irregular periods of estrus to due E produced by follicles
what is the average day of the first ovulation of the year in CO
May 1
when do mares ovulate
1-2 days before going out of heat (estrus?)
the dominant follicle grows ____ mm a day
3-5 mm
what is the postparum estrus in the horse
no lactational anestrus (unlike cattle)
first ovulation 9-10 days post foaling “foal heat” it is FERTILE
when does the mare have an LH peak?
AFTER ovulation – other species have LH peak before ovulation
where does ovulation occur in the mare
ovulation fossa
all other species occurs ovary surface
what is the fall transition period?
irregular waves of follicular development
regression without ovulation
behaviors of mare estrus
winking
raising tail
passive urination
mating posture
behaviors of mare diestrus
pin ears
kick
switch tail
vocalize
moving away from stallion
US findings of a mare in estrus
uterine edema
follicles
US findings of a mare in diestrus
CL
no edema in uterus
how can you stimulate follicular growth in the mare
light therapy in late Nov/early Dec leads to ovulation early Feb
5 types of breeding management in the mare
natural cover
pasture breeding
hand mating
timed insemination
AI
what is the ONLY breeding technique allowed by thoroughbred racehorse mares if foal registered through the jockey club
natural cover
