Browning R, Robert B S, Lewis A W, Neuendorff D A, Randel R D
Texas Agricultural Experiment Station, Overton 75684.
J Anim Sci. 1994 Apr;72(4):984-9. doi: 10.2527/1994.724984x.
Brahman cows were used to evaluate the effects of postpartum nutrition and suckling on reproductive and calf performance. Cows received high or low TDN and once-daily or unrestricted suckling. High TDN (H; 111% of NRC recommendation) cows received a 75% corn: 25% soybean meal diet. Low TDN (L; 93% of NRC recommendation) cows received no concentrates. Once-daily suckled (restricted, R) cows nursed calves for 30 min/d starting at d 21 after calving. In the unrestricted (U) suckling groups, calves had continuous access to cows. By 2 wk of suckling restriction, more (P < .01) R than U cows had progesterone concentrations of > or = .7 ng/mL (55 vs 0%) and more (P < .05) HR than LR cows had progesterone concentrations > or = .7 ng/mL (70 vs 40%). All groups had increases in progesterone and 13,14-dihydro-15-keto-prostaglandin F2 alpha before estrus. The interval to first estrus was shorter (P < .01) for R than for U cows (42 vs 65 d). By d 42 postpartum, more (P < .01) R than U cows exhibited estrus (67 vs 0%), and more (P < .05) HR than LR cows exhibited estrus (89 vs 44%). Calving interval was shorter (P < .01) for R than for U cows (361 vs 395 d). Initial ADG were lower (P < .01) for R than for U calves (.02 vs .69 kg), but weaning weights were similar. Once-daily suckling permitted ovarian activity, hastened return to estrus, and reduced calving interval without reducing weaning weights. Increased postpartum energy intake enhanced the response to restricted suckling.
婆罗门牛被用于评估产后营养和哺乳对繁殖性能及犊牛生长性能的影响。母牛被给予高或低可消化总养分（TDN），并分为每日一次哺乳或自由哺乳组。高TDN（H；为美国国家研究委员会（NRC）推荐量的111%）组的母牛采食75%玉米与25%豆粕的日粮。低TDN（L；为NRC推荐量的93%）组的母牛不采食精料。每日一次哺乳（限制哺乳，R）组的母牛在产犊后第21天开始，每天让犊牛哺乳30分钟。在自由哺乳（U）组中，犊牛可随时接触母牛。到哺乳限制2周时，R组中孕酮浓度≥0.7 ng/mL的母牛比U组更多（P < 0.01）（55%对0%），且高TDN R（HR）组中孕酮浓度≥0.7 ng/mL的母牛比低TDN R（LR）组更多（P < 0.05）（70%对40%）。所有组在发情前孕酮和13,14 - 二氢 - 15 - 酮 - 前列腺素F2α均升高。R组母牛至首次发情的间隔比U组短（P < 0.01）（42天对65天）。到产后42天时，R组表现出发情的母牛比U组更多（P < 0.01）（67%对0%），且HR组表现出发情的母牛比LR组更多（P < 0.05）（89%对44%）。R组的产犊间隔比U组短（P < 0.01）（361天对395天）。R组犊牛的初始平均日增重（ADG）比U组低（P < 0.01）（0.02千克对0.69千克），但断奶体重相似。每日一次哺乳可使卵巢活动正常，加快发情恢复，并缩短产犊间隔，同时不降低断奶体重。产后能量摄入增加可增强对限制哺乳的反应。
