Follicle growth, corpus luteum function and their effects on embryo development in postpartum dairy cows.

摘要: Absent or irregular ovarian cycles in lactating dairy cows are caused by failure to ovulate the dominant follicle at appropriate time. The then either regresses develops into a cyst. This process can be triggered variety of metabolic and disease factors that act hypothalamus pituitary gland inhibit pulsatile LH secretion surge, ovary reduce follicular growth oestradiol production. Cows poor energy status have low circulating concentrations insulin-like factor I (IGF-I). Predisposing include calving difficulties, inappropriate diet, reduced intake dry matter high rate body condition score loss. Various stressors predispose cyst development inhibiting surge ovulation; these common infections, such as mastitis. Even when ovulation does occur, may result production an inadequate corpus luteum. timing increase progesterone early luteal phase (days 4-5) appears key determinant fertility, probably because it alters secretory activity reproductive tract, thus influencing embryonic interferon-tau A period negative balance after fertility even though parameters apparently improved time service.