真胃梯度酪蛋白钠灌注对奶山羊泌乳性能和乳腺组织氨基酸吸收利用的影响

Effects of Abomasal Caseinate Infusion on Lactation Performance and Amino Acids Utilization by Mammary Glands in Dairy Goats

血液中游离的氨基酸为乳蛋白合成的主要前提物，乳腺组织氨基酸的供给和吸收影响乳蛋白的合成。本文以4只奶山羊为试验动物，采用4×4拉丁方试验设计，试验处理为真胃灌注不同数量的酪蛋白钠，对动脉血液中各种游离氨基酸的浓度、乳腺组织氨基酸提取率以及乳蛋白质合成效率进行了测定。试验结果表明，动脉血浆游离必需氨基酸浓度，除Arg外，均随酪蛋白钠灌注量的升高而升高（P〈0.05）。动脉血浆必需氨基酸浓度升高的幅度不同，最大灌注量组与对照组比较，Ile、Leu和Lys的浓度增加了2倍左右，Met增加了58.33%，Thr增加了32.5%，Phe增加了29.87%，His增加了61.66%。乳腺组织对Arg、Thr、Lys、Leu和Phe的提取率随着真胃酪蛋白灌注量的增加而明显升高（P〈0.05），对其他EAA的提取率没有显著影响（P〉0.05）。乳腺组织对不同必需氨基酸的提取率差异很大，在未灌注酪蛋白钠时各种EAA乳腺提取率的变化范围为9.18%-33.89%，泌乳反刍动物小肠可消化氨基酸理想构成应不同于乳蛋白的氨基酸构成。

Free AA in blood are considered to be the major precursors of milk protein synthesis, the mammary gland blood supply and uptake of the profile amino acids affect milk protein synthesis. Different amounts of caseinate sodium were infused abomasally into milking dairy goats and concentrations in the plasma of jagular artery, uptake rates and utilization by mammary glands of individual amino acids were measured in the present study to evaluate the change of absorbable amino acid profile in the g. i. tract before amino acids were absorbed into the mammary glands. The results indicated that the concentrations of all the amino acids,except that of Arg,in the plasma of jagular artery were increased with the increase of caseinate sodium infused （P〈0. 05）. The increment of concentration in jagular artery plasma differed with amino acids. For Ile, Leu, and Lys,the concentrations increased about two-folds when 99 g/d caseinate sodium were infused per goat compared to the control. But the concentrations of Met, Thr, Phe, and His only increased 58.33 %, 32.5 %, 29.87 %, and 61.66 % respectively at the same time. The percentages of free Arg,Thr,Lys,Leu,and Phe uptake by the mammary glands from artery plasma increased with caseinante sodium infusion （P〈0.05）, but those of other free essential amino acids measured did not differ significantly among treatments （P〉0.05）. The percentages of free non-essential amino acids uptake by the mammary glands from artery plasma differed with individual amino acids,and the range was 9.18% -33.89% in the control group.