Physiological mechanisms controlling anestrus and infertility in postpartum beef cattle.

摘要: Postpartum infertility is caused by four factors: general infertility, lack of uterine involution, short estrous cycles and anestrus. The component common to any cycle reduces potential fertility 20 30%. Incomplete involution prevents fertilization during the first d after calving but not related Short prevent 40 causing cow return estrus before pregnancy recognition occurs. Anestrus major postpartum affected several minor season, breed, parity, dystocia, presence a bull, palpation carryover effects from previous as well two suckling nutrition. These factors have direct on anestrus also interact with one or more other control Physiological mechanisms associated involve blockage GnRH "pulse generator" in hypothalamus, pathways must be involved because bypassing pulse generator an effective treatment for all cows. primary cause probably different stages mediating are prolactin, oxytocin, adrenal neural input mammary gland at least partially blood glucose endogenous opioid peptide system. Management options decrease impact include: 1) restrict breeding season less than equal 45 d; 2) manage nutrition so body condition score 5 7 calving; 3) minimize dystocia stimulate activity sterile bull synchronization; 4) judicious use complete, partial short-term weaning.