Webel D M, Johnson R W, Baker D H
Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, Illinois 61801, USA.
J Nutr. 1998 Oct;128(10):1760-6. doi: 10.1093/jn/128.10.1760.
Exposure of animals to infectious agents induces immune responses that result in reductions in food consumption and weight gain. The effect of these changes on amino acid requirements and utilization remains unclear. Three assays were conducted with young chicks with Escherichia coli lipopolysaccharide (LPS) used to stimulate the immune system. An initial study was conducted to evaluate the effects of LPS on animal performance. In a daily or alternate day injection regimen for 9 d, chicks were given intraperitoneal injections of sterile saline containing 0, 100 or 400 microgram LPS. Administration of 100 or 400 microgram LPS daily, or every other day, decreased both weight gain and food consumption. In two subsequent growth assays, chicks were fed graded levels of lysine or threonine and injected with either 0 or 400 microgram LPS every other day to evaluate the effect of LPS administration on the efficiency of amino acid utilization. At the three lowest amino acid doses, whole-body protein accretion was a linear function of supplemental lysine or threonine intake, and slopes of the accretion curves were not altered by LPS administration. The dietary lysine concentration required to maximize protein accretion was unaffected by LPS, but the absolute lysine intake required to maximize chick performance was lower in LPS-injected chicks than in saline-injected chicks. These results show that LPS administration reduces weight gain, food intake, efficiency of food utilization and the absolute quantity of lysine required to maximize these criteria. However, LPS administration does not affect the efficiency of amino acid utilization, nor does it affect the concentration of dietary lysine required to maximize performance.
动物接触传染性病原体可诱导免疫反应，导致食物摄入量和体重增加减少。这些变化对氨基酸需求和利用的影响尚不清楚。对幼雏进行了三项试验，使用大肠杆菌脂多糖（LPS）刺激免疫系统。最初进行了一项研究，以评估LPS对动物性能的影响。在为期9天的每日或隔日注射方案中，给雏鸡腹腔注射含0、100或400微克LPS的无菌盐水。每日或隔日给予100或400微克LPS，会降低体重增加和食物摄入量。在随后的两项生长试验中，给雏鸡饲喂不同水平的赖氨酸或苏氨酸，并每隔一天注射0或400微克LPS，以评估LPS给药对氨基酸利用效率的影响。在三个最低氨基酸剂量下，全身蛋白质积累是补充赖氨酸或苏氨酸摄入量的线性函数，且LPS给药不会改变积累曲线的斜率。使蛋白质积累最大化所需的日粮赖氨酸浓度不受LPS影响，但使雏鸡性能最大化所需的绝对赖氨酸摄入量在注射LPS的雏鸡中低于注射盐水的雏鸡。这些结果表明，给予LPS会降低体重增加、食物摄入量、食物利用效率以及使这些标准最大化所需的赖氨酸绝对量。然而，给予LPS不会影响氨基酸利用效率，也不会影响使性能最大化所需的日粮赖氨酸浓度。
