前期不同代谢能和粗蛋白质水平对肉鸡生产性能和产肉消耗蛋白质和能量的影响

Effects of different metabolizable energy and crude protein levels in the early stage on production performance and protein and energy consumption of meat production of broiler chickens

为研究前期日粮中不同代谢能和粗蛋白质水平对肉鸡全期生产性能和产肉所耗蛋白质和代谢能的影响,试验共选用936只1日龄雄性AA+肉鸡,前期(1~21 d)采用3×4两因子试验设计,分别为3个代谢能水平(2800、2900 kcal/kg和3000 kcal/kg),4个粗蛋白质水平(20%、21%、22%和24%),后期(22~42 d)饲喂同一日粮,试验期为42 d。结果表明:前期不同代谢能和粗蛋白质水平对肉鸡22~42日龄体增重(BWG),1~42日龄BWG、料重比(F/G)和欧洲指数,42日龄胸肌率、腿肌率、产肉量以及腿肌脂肪含量均存在显著互作效应(P<0.05)。饲喂粗蛋白质水平为20%和代谢能水平为2900 kcal/kg日粮的肉鸡22~42日龄和1~42日龄BWG、F/G以及42日龄胸肌率、腿肌率、产肉量以及胸肌和腿肌内蛋白和脂肪含量与高粗蛋白质水平组相比均无显著差异(P>0.05)。饲喂粗蛋白质水平为20%和代谢能水平为2900kcal/kg日粮的肉鸡22~42日龄BWG显著高于粗蛋白质水平为20%代谢能水平为2800kcal/kg或3000kcal/kg,以及粗蛋白质水平为24%代谢能水平为2900kcal/kg或3000kcal/kg的肉鸡(P<0.05),且1~42日龄BWG显著高于粗蛋白质水平为20%、代谢能水平为2800 kcal/kg或3000 kcal/kg的肉鸡(P<0.05)。饲喂粗蛋白质水平为22%和代谢能水平为2900 kcal/kg日粮的肉鸡1~42日龄F/G最高和欧洲指数最低(P<0.05),而粗蛋白质水平为24%、代谢能水平为3000 kcal/kg日粮的肉鸡1~42日龄F/G最低和欧洲指数最高(P<0.05)。饲喂粗蛋白质水平为20%和代谢能水平为2800 kcal/kg,以及粗蛋白质水平为21%和代谢能水平为3000 kcal/kg日粮的肉鸡42日龄腿肌率显著高于粗蛋白质水平为22%和代谢能水平为2900kcal/kg或3000kcal/kg,以及粗蛋白质水平为24%和代谢能水平为2800kcal/kg日粮的肉鸡(P<0.05)。饲喂粗蛋白质水平为20%和代谢能水平为2900 kcal/kg日粮的肉鸡42日龄胸肌率显著高于粗蛋白质水平为20%和代谢能水平为3000 kcal/kg,粗蛋白质水平为22%和代谢能水平为3000kcal/kg,以及粗蛋白质水平为24%和代谢能水平为2900 kcal/kg或3000 kcal/kg日粮的肉鸡(P<0.05),但与饲喂粗蛋白质水平为21%日粮的肉鸡无显著差异(P>0.05)。从产肉效果来说,饲喂粗蛋白质水平为21%、22%和24%日粮的肉鸡产肉量显著高于粗蛋白质水平为20%和代谢能水平为3000 kcal/kg日粮的肉鸡(P<0.05)。此外,前期饲喂不同粗蛋白质水平日粮对肉鸡每千克产肉所消耗饲料粗蛋白量有显著影响(P<0.01),与粗蛋白质水平为22%和24%的日粮相比,粗蛋白质水平为20%和21%的日粮可显著降低肉鸡每千克产肉所消耗日粮粗蛋白量(P<0.01)。综上所述,虽然前期高粗蛋白质和高代谢能水平的日粮有利于改善肉鸡欧洲指数和F/G,但肉鸡前期日粮中粗蛋白质和代谢能水平分别为21%和3000 kcal/kg可提高肉鸡22~42日龄和1~42日龄BWG、欧洲指数以及42日龄胸肌率,降低每千克产肉所消耗日粮粗蛋白量,且胸肌和腿肌内蛋白和脂肪含量提高,有助于改善鸡肉风味。因此,建议肉鸡前期日粮中粗蛋白质和代谢能水平分别为21%和3000 kcal/kg。

The purpose of this experiment was to study the effects of different AME and crude protein levels in the earlystage diet on the performance of broilers during the whole period and the protein and AME consumed in meat production.A total of 9361-day-old male AA+broilers were selected for the experiment,and a 3×4 two-factor experimental design was used in the early stage(1~21 d)with three AME levels(2800,2900 kcal/kg and 3000 kcal/kg)and four crude protein levels(20%,21%,22% and 24%),and in the late stage(22~42 d)with the same diets for an experimental period of 42 days.The results showed that there were significant(P<0.05)interaction effects of different AME and crude protein levels on broiler body weight gain(BWG)at 22~42 days of age,BWG,feed/gain ratio(F/G)and European index at 1~42 days of age,breast muscle rate,leg muscle rate,meat yield and the fat content of the leg muscle at 42 days of age.Compared with the high crude protein levels group,broilers fed diets with the crude protein level of 20% and the AME level of 2900 kcal/kg had no significant effects on BWG and F/G at 22~42 days and 1~42 days of age,and breast muscle rate,leg muscle rate,meat yield,and the protein and fat content of the breast and leg muscles at 42 days of age of broilers(P>0.05).The BWG of broilers fed diets with the crude protein level of 20% and the AME level of 2900 kcal/kg at 22~42 days of age was significantly higher than that of broilers fed diets with the crude protein level of 20% and the AME level of 2800 kcal/kg or 3000 kcal/kg(P<0.05),as well as the crude protein level of 24% and the AME level of 2900 kcal/kg or 3000 kcal/kg(P<0.05),and the BWG at 1~42 days of age was significantly higher than the crude protein level of 20% and the AME level of 2800 kcal/kg or 3000kcal/kg of broilers(P<0.05).Broilers fed a diet with the crude protein level of 22% and the AME level of 2900 kcal/kg had the highest F/G and the lowest European index at 1~42 days of age(P<0.05),while those with the crude protein level of 24% and the AME level of 3000 kcal/kg had the lowest F/G and the highest European index at 1~42 days of age(P<0.05).The leg muscle rate at 42 days of age of broilers fed a diet with the crude protein level of 20%and the AME level of 2800 kcal/kg,and the crude protein level of 21% and the AME level of 3000 kcal/kg was significantly higher than that of broilers with the crude protein level of 22% and the AME level of 2900 kcal/kg or 3000 kcal/kg,and the crude protein level of 24% and the AME level of 2800 kcal/kg(P<0.05).The breast muscle rate at 42 days of age of broilers fed a diet with the crude protein level of 20% and the AME level of 2900 kcal/kg was significantly higher than that of the diets with the crude protein level of 20% and the AME level of 3000 kcal/kg,the crude protein level of 22% and the AME level of 3000 kcal/kg,and the crude protein level of 24% and the AME levels of 2900 kcal/kg or 3000 kcal/kg(P<0.05),but there was no significant difference compared with broilers fed a diet with the crude protein level of 21%(P>0.05).In terms of meat production effect,the meat production of broilers fed diets with the crude protein levels of 21%,22% and 24% was significantly higher than that of broilers fed diets with the crude protein levels of 20% and the AME level of 3000 kcal/kg(P<0.05).In addition,feeding diets with different crude protein levels in the early stage had a significant impact on the amount of feed crude protein consumed by broilers per kilogram of meat production(P<0.01).Compared with diets with the crude protein levels of 22% and 24%,diets with the crude protein levels of 20% and 21% significantly reduced the amount of dietary crude protein consumed by broilers per kilogram of meat produced(P<0.01).In summary,although the diet with high crude protein and high AME levels in the early stage was beneficial to improving the European index and F/G of broilers,the crude protein level of 21% and the AME level of 3000 kcal/kg in the early stage diet of broilers,which could increase the BWG,European index at 22~42 days and 1~42 days of age and breast muscle rate at 42 days of age of broilers,reduce the amount of dietary crude protein consumed per kilogram of meat production,and there was no significant difference on the protein and fat content of breast and leg muscles compared with high protein group.Therefore,it was recommended that the crude protein and the AME levels in the early diet of broiler chickens were 21%and 3000 kcal/kg respectively.