The aim of this experiment was to explore the effect and mechanism of LPS on distribution of free amino acid of plasma in dairy goats fed high concentrate feed. Six dairy goats during the dry period ,which were installed permanent rumen fistulas, were randomly divided into two groups including low concentrate group (concentrate-to-forage ratio 4 : 6) and high concentrate group(concentrate-to-forage ratio 6 :4). Using a crossover experimental design divided into two phases, each phase was fourteen days. Rumen fluid pH , the content of LPS and free amino acids were determined in the first three weeks of the experiment. The results showed that those goats fed with high concentrate began to appear subacute ruminal acidosis (SARA) from the third week, and their LPS contents in peripheral blood significantly increased (F<0. 05). The content changes of each amino acid in the plasma also were found. Compared with low concentrate group, both Glu and Ala contents were significantly lower (P <0. 01), Gln, Arg, Thr, Lys, total non-essential amino acids, total free amino acids and total glucogenic amino acids significantly decreased (P<0. 05). These results indicated that amino acids in plasm of goats appeared to distribution as the increased the proportion of concentrated feed in the diet. Its mechanism may be related to the decrease of pH in rumen and the increase of LPS in blood.%为了探讨高精料饲喂产生LPS对奶山羊血浆游离氨基酸重分配的影响及其机制,本研究选用奶山羊6只,随机分为2组,分别饲喂精粗比为4∶6(低精料组)和6 ∶4(高精料组)的日粮,交叉试验设计,分2期进行,每期14 d.在试验第3周测定瘤胃液pH、血液中LPS含量和游离氨基酸含量.结果表明,自第3周,高精料组山羊开始出现亚急性瘤胃酸中毒,外周血液中LPS含量显著升高(P＜0.05)；血浆中各氨基酸含量均发生变化,表现为Glu、Ala含量极显著降低(P＜0.01),Gin、Arg、Thr、Lys、总非必需氨基酸、总游离氨基酸、总生糖氨基酸均显著低于低精料组(P＜0.05).结果提示,饲粮中精饲料比例增加,血浆氨基酸发生重分配,其机理可能与瘤胃pH下降和血液中LPS含量升高有关.
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