Huyler M T, Kincaid R L, Dostal D F
Department of Animal Sciences, Washington State University, Pullman 99164-6310, USA.
J Dairy Sci. 1999 Mar;82(3):527-36. doi: 10.3168/jds.S0022-0302(99)75264-1.
The effects of concentration of rumen-undegradable protein (RUP) in prepartum diets on performance and metabolic measures were determined. Pregnant, nonlactating cows were assigned to one of three dietary treatments that differed in concentrations of crude protein and RUP. The crude protein and RUP percentages (dry matter basis) in the diets were 11.7 and 3.1%, 15.6 and 6.8%, and 20.6 and 10.6%, which were identified as low, medium, and high protein diets, respectively. Dietary treatments were initiated 6 wk prior to expected calving date and were fed until parturition. All cows were fed similar postpartum diets through wk 10 of lactation. Prepartum intakes of dry matter and rumen-degradable protein were similar among treatments. Yields of milk, protein, and fat were not affected by prepartum RUP. Concentrations of plasma urea N in cows fed the medium and high protein diets were elevated during the prepartum period even though intakes of rumen-degradable protein were similar for cows on all treatments. Cows fed the medium and high protein diets had greater prepartum concentrations of Val, Ile, and Leu but not other essential amino acids in plasma. Dietary treatments did not affect prepartum or postpartum contents of triglycerides in liver or plasma nonesterified fatty acid concentrations. Thus, supplemental RUP fed to cows for 6 wk prepartum affected protein metabolism but not measures of energy metabolism.
测定了产前日粮中瘤胃不可降解蛋白（RUP）浓度对生产性能和代谢指标的影响。将怀孕的非泌乳奶牛分配到三种日粮处理组之一，这三种处理组的粗蛋白和RUP浓度不同。日粮中粗蛋白和RUP的百分比（干物质基础）分别为11.7%和3.1%、15.6%和6.8%、20.6%和10.6%，分别被确定为低蛋白、中蛋白和高蛋白日粮。日粮处理在预计产犊日期前6周开始，一直饲喂至分娩。所有奶牛在泌乳第10周前都饲喂相似的产后日粮。各处理组之间产前干物质和瘤胃可降解蛋白的摄入量相似。产前RUP对牛奶、蛋白质和脂肪的产量没有影响。尽管所有处理组奶牛的瘤胃可降解蛋白摄入量相似，但饲喂中蛋白和高蛋白日粮的奶牛在产前血浆尿素氮浓度升高。饲喂中蛋白和高蛋白日粮的奶牛产前血浆中缬氨酸、异亮氨酸和亮氨酸的浓度较高，但其他必需氨基酸的浓度没有升高。日粮处理对肝脏中甘油三酯的产前或产后含量或血浆非酯化脂肪酸浓度没有影响。因此，产前6周给奶牛补充RUP会影响蛋白质代谢，但不会影响能量代谢指标。
