Erasmus L J, Botha P M, Meissner H H
Irene Animal Production Institute, Republic of South Africa.
J Dairy Sci. 1994 Dec;77(12):3655-65. doi: 10.3168/jds.S0022-0302(94)77310-0.
Four lactating Holstein cows, fitted with T-type cannulas in the proximal duodenum, were used in a 4 x 4 Latin square design to determine the effect of protein supplement on production, ruminal digestion, and profile and the quantity of AA available for absorption. Supplemental protein sources were blood meal, corn gluten meal, blood meal plus corn gluten meal, and sunflower meal, which constituted 8, 10.5, 9.3, and 13% of dietary DM, respectively. The DMI and milk production were not influenced by treatment. Ruminal NH3 concentration increased with the sunflower meal diet, and molar percentage of propionate decreased with the blood meal diet. Duodenal flow of NAN was unaffected by protein source, but dietary N flow decreased, and bacterial N flow increased, when cows were fed the sunflower meal diet. Bacterial N flows were 46.0, 45.3, 46.4, and 65.8% of NAN for the respective diets. The AA profiles of isolated ruminal bacteria differed among dietary treatments but were not correlated with the respective supplementary protein sources. The essential AA profiles of duodenal digesta and duodenal flow of individual AA closely reflected AA differences in protein sources, suggesting that the composition of RUP profoundly affected the composition of protein entering the intestine when supplemental protein provided 35% of total CP intake.
选用4头装有十二指肠近端T型套管的泌乳荷斯坦奶牛，采用4×4拉丁方设计，以确定蛋白质补充料对生产性能、瘤胃消化、氨基酸可吸收量及氨基酸组成的影响。补充蛋白质来源分别为血粉、玉米蛋白粉、血粉加玉米蛋白粉和向日葵粕，分别占日粮干物质的8%、10.5%、9.3%和13%。处理对干物质采食量和产奶量没有影响。向日葵粕日粮组瘤胃氨浓度升高，血粉日粮组丙酸摩尔百分比降低。蛋白质来源对十二指肠非氨氮流量没有影响，但饲喂向日葵粕日粮时，日粮氮流量降低，细菌氮流量增加。各日粮细菌氮流量分别占非氨氮的46.0%、45.3%、46.4%和65.8%。不同日粮处理下分离的瘤胃细菌氨基酸组成不同，但与相应的补充蛋白质来源无关。十二指肠消化物的必需氨基酸组成和各氨基酸的十二指肠流量密切反映了蛋白质来源中的氨基酸差异，表明当补充蛋白质占总粗蛋白摄入量的35%时，瘤胃非降解蛋白的组成深刻影响进入肠道的蛋白质组成。
