低蛋白日粮添加蛋氨酸对肉鸡生产性能、氮代谢及血液生化指标的影响

Effect of low protein diets supplemented with Met on growth performance, nitrogen metabolism and blood biochemical parameters

试验旨在研究低蛋白日粮添加蛋氨酸对肉鸡生产性能、氮代谢及血液生化指标的影响。将300只1日龄科宝肉鸡随机分成5组,每组4个重复,每个重复15只鸡。正对照组饲喂正常蛋白水平的日粮;负对照组饲喂低蛋白日粮(比正对照组低3个百分点);试验组是在负对照组的基础上分别添加0.1%、0.2%、0.3%三个水平的蛋氨酸,采用两阶段饲养。试验结果表明:随着蛋氨酸添加水平的提高,①日增重有上升的趋势,其中在前期以0.2%添加量最高(P【0.05),后期差异不显著。②后期日采食量较负对照组有下降的趋势,0.3%的添加量采食量最低(P【0.05),前期差异不显著。③料肉比,前期、中期和全期试验组与负对照组差异显著(P【0.05)。④在22~42日龄时添加蛋氨酸显著降低了氮排出量(P【0.05),同时两个饲养阶段试验组的氮沉积率较正、负对照组显著提高(P【0.05)。⑤试验组较负对照组血清尿酸和总蛋白含量均有所升高。试验结果说明,在本试验中,低蛋白日粮可以通过适量添加蛋氨酸提高生产性能和氮沉积率,并影响机体蛋白沉积。

The experiment was conducted to investigate the effect of low protein diets supplemented with DL-Methionine(Met)on growth performance, nitrogen metabolism and blood biochemical parameters of broilers.Three hundred1-d-old Cobb broilers were allocated in 5 experimental treatments for 6 w. Each treat.ment had 4 replicates of 15 broilers each. Chickens in the positive control group received a diet with protein of a normal level, while the negative received a diet with a protein level which was 3% lower than the positive.Chickens in the experimental groups got a diet based on the negative control group diet, which contained Met0.1%, 0.2%, 0.3%,respectly. The experiment lasted for 6 w( early period for 1~21 d and later period for 22~42 d). The results showed that: with the Met level increasing, ①Average daily gain(ADG)had an increasing tendency. ADG during the earlier period in the Met 0.2% group was highest(P<0.05)while during the later period no difference was found.②Average daily feed intake(ADFI)during the later period showed a decreas.ing tendency as the Met 0.3% group had the lowest level(P<0.05). But there was no difference during the ear.lier period.③Feed conversion rate(FCR)showed a significant difference during the earlier period, the later period and the whole period(P<0.05).④During the later period, chickens in the experimental group had sig.nificant lower nitrogen excretion, while nitrogen depo.sition rate was higher(P<0.05)than the control groups during the whole period. ⑤ As for uric acid and total protein in the serum, the experimental groups had a higher level than the control group, with no significance. All these can be explained:Adding the right amount of Met in the low protein feed canimprove the growth performance and nitrogen deposition ratemeanwhile it can affecbody protein deposition.