Embryo recovery from exercised mares.
The effect of exercise on mare reproductive efficiency was evaluated by comparing rates of embryo recovery from mares assigned to either an exercise regimen or a non-exercise (control) regimen. Exercised mares were worked daily for 30 min under average ambient conditions of >30 degrees C and >50% humidity. Mares were inseminated during estrus and subjected to uterine flush for embryo recovery on d 7 after ovulation for two consecutive cycles. After this, mares were allocated to the opposite group and allowed an estrous cycle without reproductive manipulation; then insemination and uterine flushing were conducted on two more consecutive cycles. Prostaglandin F(2alpha) was administered on the day of uterine flush. Mare rectal temperature increased during exercise from a mean of 38 degrees C to a mean of 39.9 degrees C. Mares had ovulations from smaller follicles when exercised than they did under control conditions (39.8+/-0.5 compared with 41.5+/-0.5mm diameter; P<0.05), and had an increased time from PGF(2alpha) administration to subsequent ovulation (8.47+/-0.337 compared with 9.27+/-0.294 d; P<0.05). Embryo recovery from control mares was 22 of 35 (63%). Fewer embryos were recovered from exercised mares (11 of 32, 34%; P<0.05). The proportion of embryos classified as Grade 1 tended to be less in exercised than in non-exercised mares (4 of 11, 36% compared with 16 of 22, 73%; P=0.051). These data indicate that exercising mares in a hot and humid environment are associated with changes in ovarian follicle development and ovulation, and a reduction in embryo recovery.
Mortensen
C J
CJ
Department of Animal Science, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX 77843-2471, USA. cmorten@clemson.edu
Choi
Y H
YH
Hinrichs
K
K
Ing
N H
NH
Kraemer
D C
DC
Vogelsang
S G
SG
Vogelsang
M M
MM
D000818:Animals; D001831:Body Temperature / Q000502:physiology; D004624:Embryo Transfer / Q000662:veterinary*; D005260:Female; D006736:Horses / Q000502:physiology*; D007315:Insemination, Artificial / Q000662:veterinary*; D008297:Male; D010062:Ovulation Induction / Q000662:veterinary*; D010805:Physical Conditioning, Animal / Q000009:adverse effects / Q000502:physiology*; D011247:Pregnancy; D011897:Random Allocation