22~42日龄黄羽肉鸡饲粮苏氨酸需要量研究

Dietary Threonine Requirement of Yellow-feathered Broilers Aged From 22 to 42 Days

【目的】通过研究饲粮苏氨酸水平对22~42日龄黄羽肉鸡生长性能、胴体品质和免疫功能的影响,确定其苏氨酸需要量。【方法】试验选用22日龄快大型岭南黄羽肉鸡1600只,根据体重相同的原则分为5个组,每组8个重复,每个重复40只肉鸡(公母各半)。采用玉米-花生粕型基础饲粮,5个处理组试验鸡分别饲喂含0.60%(基础饲粮)、0.67%、0.74%、0.81%和0.88%苏氨酸饲粮,试验期为21 d。试验结束后,每个重复选取2只鸡屠宰采样,测定屠宰性能、免疫器官指数和血清生化指标。【结果】饲粮苏氨酸水平显著影响黄羽肉公鸡、母鸡的体重、平均日增重和料重比(P<0.05)。对于母鸡,0.88%苏氨酸水平组平均日增重最高;0.81%苏氨酸水平组平均日采食量最高。对于公鸡,0.81%苏氨酸水平组平均日增重最高;0.81%苏氨酸水平组平均日采食量最高。饲粮苏氨酸水平与黄羽肉公鸡平均日增重、平均日采食量以及公、母鸡料重比呈显著的二次线性相关(P<0.05);根据平均日增重和平均日采食量回归方程得出黄羽肉公鸡饲粮苏氨酸最适水平分别为0.81%和0.83%;根据料重比回归方程得出黄羽肉母鸡和公鸡饲粮苏氨酸最适水平分别为0.83%和0.86%。饲粮苏氨酸水平对黄羽肉公鸡、母鸡的全净膛率、半净膛率、腿肌率、胸肌率均无显著影响(P>0.05);对黄羽肉公鸡全净膛率和腹脂率均有显著影响,其中0.81%苏氨酸组全净膛率显著高于0.60%和0.74%苏氨酸组,0.88%苏氨酸组腹脂率显著低于0.60%和0.67%苏氨酸组(P<0.05)。饲粮苏氨酸水平显著影响黄羽肉母鸡法氏囊指数和胸腺指数,其中0.60%苏氨酸组法氏囊指数显著低于0.81%苏氨酸组,0.81%和0.88%苏氨酸组胸腺指数显著高于0.60%苏氨酸组(P<0.05);对肝脏指数、脾脏指数无显著影响(P>0.05)。饲粮苏氨酸水平对黄羽肉母鸡血清中甘油三酯、胰岛素含量有显著影响,其中0.60%苏氨酸水平组血清中胰岛素含量最低,0.88%苏氨酸水平组血清中甘油三酯含量最低,显著低于0.60%苏氨酸组(P<0.05);苏氨酸水平对黄羽肉公鸡甘油三酯含量有显著影响,其中0.88%苏氨酸水平组血清中甘油三酯含量最低,显著低于0.60%和0.67%苏氨酸组(P<0.05)。【结论】饲粮中添加适量苏氨酸可以提高黄羽肉鸡生长性能、胴体品质,促进免疫器官发育。以生长性能为主要判定指标,确定22~42日龄黄羽肉母鸡饲粮最适苏氨酸水平为0.83%,黄羽肉公鸡最适苏氨酸水平为0.81%。

【Objective】 This experiment was conducted to investigate the effects of dietary threonine(THR)level on growth performance, carcass quality and immune function of Yellow-feathered broilers aged from 22 to 42 days, and to determine their appropriate THR requirement.【Method】 A total of 1 600 22-day-old fast-growing Lingnan Yellow-feathered broilers were randomly divided into 5 groups with 8 replicates per group and 40 chickens(male and female half) per replicate according to the same body weight.Chickens in the 5 treatment groups were fed diets containing 0.55%(basal diet),0.62%,0.69%,0.76% or 0.83% THR,respectively.A corn-peanut meal basal diet was adopted, and the experiment lasted for 21 days.At the end of the test, 2 chickens were selected for slaughter sampling in each repetition to determine slaughter performance, immune organ index and serum biochemical indicators. 【Result】 Dietary THR level significantly affected body weight(BW),average daily gain(ADG) and feed/gain(F/G)(P<0.05).For female broilers, ADG of 0.88% THR group was the highest, and average daily feed intake(ADFI) of 0.81% THR level group was the highest.For male broilers, ADG of 0.81% THR group was the highest, and ADFI of 0.81% THR level group was the highest.There was a significant quadratic linear correlation between dietary THR level and ADG,ADFI of Yellow-feathered males and F/G of both males and females(P<0.05).According to the regression equation of ADF and ADFI,the optimal dietary THR level of Yellow-feathered male broilers was 0.81% and 0.83%,respectively.According to the regression equation of F/G,the optimal dietary THR level of Yellow-feathered male broilers was 0.83% and 0.86%,respectively.Dietary THR level had no significant effects on eviscerated percentage, half-eviscerated percentage, leg muscle percentage and breast muscle percentage of Yellow-feathered males and females(P<0.05).There were significant effects on eviscerated percentage and abdominal fat percentage of Yellow-feathered male broilers, the abdominal fat percentage in 0.81% THR group was significantly lower than that in 0.60% and 0.74% THR groups, and the abdominal fat percentage in 0.88% THR group was significantly lower than that in 0.60% and 0.67% THR groups(P<0.05).Dietary THR level significantly affected bursa of Fabricius index and thymus index of Yellow-feathered females, the bursa of Fabricius index in 0.60% THR group was significantly lower than that in 0.81% THR group, and the thymus index in 0.81% and 0.88% THR groups were significantly higher than that in 0.60% THR group(P<0.05),but had no significant effects on liver index and spleen index(P>0.05).Dietary THR level had significant effects on serum triglyceride and insulin contents of Yellow-feathered female broilers, serum insulin content of 0.60% THR level group was the lowest, the serum triglyceride content in 0.88% THR level group was the lowest, significantly lower than 0.60% THR level group(P<0.05).Dietary THR level significantly affected the triglyceride content of Yellow-feathered male broilers, and 0.88% THR level group had the lowest serum triglyceride content, significantly lower than 0.60% and 0.67% THR level groups(P<0.05).【Conclusion】 Appropriate dietary THR could improve the growth performance, carcass quality and immune organ development of Yellow-feathered broilers.The optimal THR level for Yellow-feathered male and female broilers aged from 22 to 42 days were determined to be 0.83% and 0.81% respectively based on growth performance, the daily requirement of threonine for male and female broilers were 0.59 g and 0.51 g, respectively.