INFLUENCE OF BODY CONDITION AT CALVING AND POSTPARTUM NUTRITION ON ENDOCRINE FUNCTION AND REPRODUCTIVE PERFORMANCE OF PRIMIPAROUS BEEF COWS

摘要: The influences of body condition score (BCS) at calving and postpartum nutrition on endocrine ovarian functions, reproductive performance, were determined by randomly allocating thin (mean BCS = 4.4 +/- 0.1) or moderate 5.1 Angus x Hereford primiparous cows to receive one two nutritional treatments after calving. Cows fed gain either 0.45 kg/d (M, n 17) 0.90 (H, for the first 71 3 d postpartum. All then M diet until 21 estrus. A replication (yr 2; M, 25; H, 23) was also used evaluate characteristics. Concentrations IGF-I, leptin, insulin, glucose, NEFA, thyroxine quantified in plasma samples collected weekly during treatment 7 wk before Estrous behavior detected radiotelemetry, luteal activity based concentrations progesterone plasma. bred AI between 14 20 h onset estrus, pregnancy assessed 35 55 ultrasonography. that calved with a 4 5 had similar function performance During treatment, H gained BW increased (P < 0.01), greater 0.05) than cows. However, not affected time. previously shorter 0.01) interval estrus ovulation, larger dominant follicle cows, but duration number mounts received influenced nutrient intake. Pregnancy rate 0.03) (76%, 38) (58%, 33) Increased intake stimulated secretion anabolic hormones, promoted fat deposition, shortened IGF-I leptin constant indicating acute changes these hormones are associated resumption beef