低蛋白质饲粮中添加不同水平亮氨酸对育肥猪氮平衡的影响

摘要

This experiment was designed to investigate the effects of low?protein diets supplemented with differ?ent levels of leucine on nitrogen balance of finishing pigs, and to determine the appropriate level of leucine in low protein diets. In experiment, ten healthy " Duroc×Landrace×Yorkshire" three?way hybrid castrated boars with an initial body weight of (70.7±3.1) kg were allocated to one of five groups in a 5 × 5 Latin square de?sign and fed 5 test diets, including one normal protein diet ( contained 14.5% crude protein) and four low pro?tein diets ( contained 10.0% crude protein) supplemented with different levels (0, 0.4%, 0.8% and 1.2%) of leucine. The whole experimental period was 50 days, which was divided into 5 phases, each phase was 10 days. The first 5 days were the pre?test period, and the last 5 days were the collection period. Determination of nitrogen balance indexes in finishing pigs by full collection of feces and urine. The results showed that the re?duction of dietary protein level resulted in a significant decrease in nitrogen intake of finishing pigs ( P＜0.05) , followed by a significant decrease in nitrogen output and nitrogen retention ( P＜0.05) , but the nitrogen reten?tion rare of four low?protein diet groups was significantly higher than that of the normal protein diet group ( P＜0.05). When 0.4% leucine was added to the low protein diet, the nitrogen output was the lowest and the nitro?gen retention was the highest; while the leucine supplemental level was higher than 0.4%, the nitrogen reten?tion decreased significantly ( P＜0.05). At the same time, the total tract apparent digestibility of isoleucine and valine showed a decrease trend with the increase of leucine supplemental level. Based on above results, the op?timum supplemental level of leucine in the low?protein diet ( contained 10.0% crude protein) of finishing pigs should be 0.4%.[ Chinese Journal of Animal Nutrition, 2019, 31(6) :2579?2588]%本试验旨在研究在低蛋白质饲粮中添加不同水平亮氨酸对育肥猪氮平衡的影响,以确定低蛋白质饲粮中亮氨酸的适宜添加水平.试验选取10头初始体重为(70.7±3.1) kg的健康杜×长×大杂交去势公猪,采用5×5拉丁方设计,饲喂5种试验饲粮,包括1个正常蛋白质饲粮(粗蛋白质含量为14.5%)和4个添加不同水平(0、0.4%、0.8%和1.2%)亮氨酸的低蛋白质饲粮(粗蛋白质含量为10.0%) .整个试验期为50 d,共分为5期,每期10 d,前5天为预试期,后5天为收集期.采用全收集粪尿法测定育肥猪的氮平衡指标.结果显示:饲粮蛋白质水平的降低导致育肥猪的氮摄入量显著降低( P＜0.05) ,继而氮排出量和氮沉积量也显著降低( P＜0.05) ,但4个低蛋白质饲粮组的氮沉积率均显著高于正常蛋白质饲粮组( P＜0.05) ;低蛋白质饲粮中添加0.4%的亮氨酸时,氮排出量最低,氮沉积量最高;而当亮氨酸添加水平高于0.4%时,氮沉积量显著下降( P＜0.05) ,同时,随着亮氨酸添加水平的升高,异亮氨酸和缬氨酸的全肠道表观消化率有下降的趋势.综合以上结果得出,育肥猪低蛋白质饲粮(粗蛋白质含量为10.0%)中亮氨酸的适宜添加水平为0.4%.