INRA, UMR1348 Pegase, F-35590 Saint-Gilles, France.
J Dairy Sci. 2012 Oct;95(10):5876-87. doi: 10.3168/jds.2011-5230. Epub 2012 Aug 9.
Providing a well-balanced supply of essential AA (EAA) can serve as an opportunity to reduce the protein intake for dairy cows by increasing the efficiency of metabolizable protein (or PDIE, its equivalent in the INRA feeding system) utilization for milk protein yield. Our objectives were to compare the effect of supplying an "ideal" EAA profile (EAA+) with an imbalanced AA profile (control) at 2 levels of PDIE/NE(L) (net energy for lactation) supplies to study the interaction between PDIE and AA profiles, and to compare this ideal profile with a simple mixture of the 4 most deficient EAA (4 EAA) in the diets of dairy cows. Six lactating multiparous Holstein cows received 6 treatments with 2 different levels of PDIE supplied by diets and AA infusions in the duodenum according to a changeover design with 3-wk periods. Within each PDIE supply level, the cows received 3 different AA infusions in the duodenum according to a 3×3 Latin square design with 1-wk subperiods, which corresponded to the following treatment groups: control (Glu), 4EAA (Lys, Met, His, Leu), and EAA+ (4 EAA plus Ile, Val, Phe, Trp, and Tyr). In the low and high PDIE treatments, diets and infusions provided 54.7 and 64.0 g/Mcal of PDIE/NE(L), respectively, which corresponded to crude protein levels of 13.6 and 15.2%, respectively. High-PDIE supplies increased the milk protein yield by 163 g/d, the milk protein content by 1.4 g/kg, the milk yield by 4.1 kg/d, and the lactose yield by 178 g/d and decreased the PDIE efficiency of utilization by 12.4%, whereas the N efficiency of utilization remained unaffected. Supplying the 2 EAA profiles (4EAA and EAA+) increased the milk protein yield by 67 g/d, the milk protein content by 1.3g/kg, and the milk yield by 0.9 kg/d, whereas the milk fat and milk lactose contents were decreased by 2.4 and 1.6g/kg, respectively. The responses regarding milk yield and its composition were similar whether the cows received the 4 EAA or the EAA+ treatment. The responses were similar for the milk yield and composition whether the EAA were supplied by low- or high-PDIE supplies. In conclusion, the efficiency of PDIE utilization was improved by 6.6% and the N efficiency was improved by 7.0% by correcting the EAA profiles, independent of the level of PDIE supplied. In addition, the increased efficiency observed, associated with provision of the 4 EAA, was similar to the provision of all EAA (EAA+) in this experiment.
提供均衡的必需氨基酸（EAA）供应，可以通过提高可代谢蛋白质（或 INRA 饲养系统中的 PDIE，其等效物）对牛奶蛋白产量的利用效率，从而减少奶牛的蛋白质摄入量。我们的目的是比较在 2 种 PDIE/NE（泌乳净能）供应水平下，提供“理想”EAA 谱（EAA+）与不平衡 AA 谱（对照）的效果，以研究 PDIE 和 AA 谱之间的相互作用，并将这种理想的谱与奶牛日粮中 4 种最缺乏的 EAA（4EAA）的简单混合物进行比较。6 头泌乳经产荷斯坦奶牛接受 6 种处理，2 种不同水平的 PDIE 通过日粮和十二指肠内 AA 输注供应，根据 3 周过渡期设计进行，每个 PDIE 供应水平内，奶牛接受 3 种不同的十二指肠内 AA 输注，根据 3×3 拉丁方设计进行，1 周亚期，对应以下处理组：对照（Glu）、4EAA（Lys、Met、His、Leu）和 EAA+（4EAA 加 Ile、Val、Phe、Trp 和 Tyr）。在低和高 PDIE 处理中，日粮和输注分别提供 54.7 和 64.0 g/Mcal PDIE/NE（L），分别对应粗蛋白水平 13.6 和 15.2%。高 PDIE 供应使牛奶蛋白产量增加 163 g/d，牛奶蛋白含量增加 1.4 g/kg，牛奶产量增加 4.1 kg/d，乳糖产量增加 178 g/d，PDIE 利用效率降低 12.4%，而氮利用效率不受影响。供应 2 种 AA 谱（4EAA 和 EAA+）使牛奶蛋白产量增加 67 g/d，牛奶蛋白含量增加 1.3g/kg，牛奶产量增加 0.9 kg/d，而牛奶脂肪和牛奶乳糖含量分别降低 2.4 和 1.6g/kg。无论奶牛接受 4EAA 还是 EAA+处理，牛奶产量和组成的反应相似。EAA 供应的水平对牛奶产量和组成的反应相似。结论是，通过校正 EAA 谱，PDIE 的利用效率提高了 6.6%，氮的利用效率提高了 7.0%，而与供应的 PDIE 水平无关。此外，在本实验中，提供 4 种必需氨基酸所观察到的效率提高与提供所有必需氨基酸（EAA+）相似。
