Wiley J S, Petersen M K, Ansotegui R P, Bellows R A
Anim. and Range Sci. Dept., Montana State University, Bozeman 59717.
J Anim Sci. 1991 Nov;69(11):4279-93. doi: 10.2527/1991.69114279x.
Two experiments were conducted in consecutive years to determine the effects of prepartum nutrient level and postpartum ruminally undegraded protein intake on nutrient status, milk production, subsequent calf production, and reproductive performance of 126 crossbred, primiparous beef heifers. Prepartum treatments were low nutrient intake (LN) (approximately 2.5 kg of TDN, .5 kg of CP animal-1.d-1 and maintenance nutrient intake (MN) (5 kg of TDN, 1 kg of CP animal-1.d-1), which were fed for 75 d before parturition. Two postpartum protein supplements were formulated to provide 250 g/d of ruminally degradable protein (RD) and one to supply ruminally undegraded protein (UD) at 250 g/d of additional UD CP compared to the RD supplement. Cholesterol was lower (P less than .01) in heifers given UD than in heifers given RD. Blood urea nitrogen was higher (P less than .01) for UD-fed heifers than for RD-fed heifers and was higher in LN heifers (P less than .06) than in MN heifers. Milk production did not differ (P greater than .11) as a result of LN, MN, UD, or RD. Postpartum cow weight gain was greatest (P less than .01) for UD and LN heifers. The percentage of heifers bred during the first estrous cycle of the breeding season was greater (P less than .02) for UD than for RD. Overall, prepartum nutrition did not interact with postpartum protein supplement, nor did it have any effect on postpartum interval, whereas UD increased cow weight gain postpartum and reduced postpartum interval.
连续两年进行了两项试验，以确定产前营养水平和产后瘤胃未降解蛋白质摄入量对126头杂交初产肉用小母牛的营养状况、产奶量、后续犊牛生产及繁殖性能的影响。产前处理为低营养摄入量（LN）（约2.5千克总可消化养分，0.5千克粗蛋白/头·天）和维持营养摄入量（MN）（5千克总可消化养分，1千克粗蛋白/头·天），在分娩前75天饲喂。配制了两种产后蛋白质补充剂，一种提供250克/天的瘤胃可降解蛋白质（RD），另一种比RD补充剂多提供250克/天的瘤胃未降解蛋白质（UD）。接受UD的小母牛的胆固醇水平低于接受RD的小母牛（P<0.01）。接受UD饲喂的小母牛的血尿素氮高于接受RD饲喂的小母牛（P<0.01），且LN小母牛的血尿素氮高于MN小母牛（P<0.06）。LN、MN、UD或RD对产奶量没有显著影响（P>0.11）。产后母牛体重增加量在UD和LN小母牛中最大（P<0.01）。繁殖季节第一个发情周期配种的小母牛百分比，UD组高于RD组（P<0.02）。总体而言，产前营养与产后蛋白质补充剂之间没有相互作用，对产后间隔也没有任何影响，而UD增加了产后母牛体重增加量并缩短了产后间隔。
