Interaction between season and culture with insulin-like growth factor-1 on survival of in vitro produced embryos following transfer to lactating dairy cows.
Culture of bovine embryos in the presence of insulin-like growth factor-1 (IGF-1) can increase pregnancy rates following transfer to heat-stressed, lactating dairy cows. The objective of the present experiment was to determine whether the effect of IGF-1 on post-transfer embryo survival was a general effect or one specific to heat stress. Lactating recipients (n=311) were synchronized for timed-embryo transfer at four locations. Embryos were produced in vitro and cultured with or without 100 ng/mL IGF-1. At Day 7 after anticipated ovulation (Day 0), a single embryo was randomly transferred to each recipient. Pregnancy was diagnosed at Day 21 by elevated plasma progesterone concentrations, at Days 27-32 by ultrasonography, and at Days 41-49 by transrectal palpation. Transfers were categorized into two seasons, hot or cool (based on the month of transfer). There was a tendency (P<0.09) for an interaction between embryo treatment and season for pregnancy rate at Day 21; this interaction was significant at Days 30 and 45 (P<0.02). Recipients receiving IGF-1 treated embryos had higher pregnancy rates in the hot season but not in the cool season. There was a similar interaction between embryo treatment and season for overall calving rate (P<0.05). There was also an interaction between season and treatment affecting pregnancy loss between Days 21 and 30; recipients that received IGF-1 treated embryos had less pregnancy loss during this time period in the hot season but not in the cool season. The overall proportion of male calves born was 77.5%. In conclusion, treatment of embryos with IGF-1 improved pregnancy and calving rates following the transfer of in vitro produced embryos into lactating recipients, but only under heat-stress conditions.
Block
J
J
Department of Animal Sciences, University of Florida, Gainesville, FL 32611-0910, USA.
Hansen
P J
PJ
D000034:Abortion, Veterinary / Q000662:veterinary; D000818:Animals; D001724:Birth Weight / Q000187:drug effects; D002417:Cattle / Q000196:embryology / Q000502:physiology*; D003470:Culture Media; D046149:Embryo Culture Techniques / Q000379:methods / Q000662:veterinary*; D004624:Embryo Transfer / Q000662:veterinary; D004622:Embryo, Mammalian / Q000187:drug effects*; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007774:Lactation; D050498:Live Birth; D008297:Male; D011247:Pregnancy; D018873:Pregnancy Rate; D012621:Seasons; D012744:Sex Ratio; D013696:Temperature; D013997:Time Factors
D003470:Culture Media; D007334:Insulin-Like Growth Factor I