| This study was conducted to investigate the effect of low protein supplemented with Methionine on some related indexes and to determine optimal addition levels of Methionine. The research can provide a theoretical basis for the design of the broiler low protein diet.Three hundred1-day-old Cobb broilers were allocated randomly in5experimental with4replicates of15broilers. Chickens in the positive received a diet with protein of a normal level, while the negative control group received a lower protein. Chickens in the experimental group added Methionine in the negative control group diet, which contained3levels,0.1%,0.2%,0.3%, respectly. The results are summarized as follws:Compared with the negative control group, the experimental groups can decrease the feed conversion ratio (P<0.05).The experimental groups improved the average daily gain in the two stages and the whole period. And the0.2%group had The highest weight gainin1-21d, however, the other group had no significant different. Each experimental group decreases the feed intake. The amount of nitrogen excretion was reduced in the two phases and the difference is significant (P<0.05). The nitrogen deposition rate increased significantly and the0.3%is the highest.Compared with the negative control group, pectoral muscle rate significantly improved (P<0.05) in experimental group, which0.2%in21d and0.3%in42d were maximum. Abdominal fat rate were reduced, whichdecreased significantly in42d. And the0.1%were the least in the two stages. The eviscerated rate was improved (P<0.05) in42d, of which0.3%was the highest. The uric acid levels were linearly increased. And the total protein content also increased in several groups; however, the difference was not significant (P>0.05).In addition to bursal index, all the immune organ index in positive control groups were higher than the others.But all groups has no significant difference. With the increase of Methionine in diets, the feather protein content and feather weight comparison tended to rise, but the difference was not significant (P>0.05); The feather protein content tended to improve in42d, but the difference was not significant (P>0.05). While the feather weight ratio declined and0.1%group was lowest.In summary, adding0.2%-0.3%to low protein diet for broilers can effectively reduce feed conversion and nitrogen emissions, increase daily gain and improve carcass quality. |
