26~45日龄竹丝鸡饲粮粗蛋白质需要量研究

Study on Dietary Crude Protein Requirement of Silky Fowl During 26 to 45 Days of Age

【目的】研究饲粮粗蛋白质水平对26~45日龄竹丝公鸡生长性能、胴体性状和血清生化指标的影响,为此生长阶段粗蛋白质精准供给提供理论基础。【方法】1625只26日龄竹丝肉公鸡根据体重一致原则分为5个处理组,每个处理组5个重复,每个重复65只鸡,各处理组饲粮粗蛋白质水平依次为18.5%、19.5%、20.5%、21.5%和22.5%,试验期20 d。每个重复于试验结束当天挑选接近平均体重的2只鸡屠宰,制备血清和分割屠体,测定胴体性状和血清生化指标。【结果】①饲粮粗蛋白质水平极显著影响肉鸡终末体重、平均日增重和料重比(P<0.01),随着粗蛋白质水平的升高,终末体重和平均日增重呈线性和二次曲线升高(P<0.01),料重比呈线性和二次曲线降低(P<0.01)。饲粮粗蛋白质水平对肉鸡平均日采食量和成活率无显著影响(P>0.05)。②饲粮粗蛋白质水平显著或极显著影响肉鸡屠宰率(P<0.01)、半净膛率(P<0.01)和全净膛率(P<0.05),但对胸肌率、腿肌率和腹脂率无显著影响(P>0.05),且屠宰率和半净膛率随粗蛋白质水平的升高呈线性和二次曲线降低(P<0.01或P<0.05)。③饲粮粗蛋白质水平极显著影响肉鸡血清胰岛素样生长因子1(IGF-1)和胆固醇(TC)含量(P<0.01),且TC含量随粗蛋白质水平的升高呈线性降低(P<0.05)。饲粮粗蛋白质水平对肉鸡血清尿素氮(BUN)和甘油三酯(TG)含量无显著影响(P>0.05)。【结论】饲粮21.5%粗蛋白质水平可改善肉鸡生长性能,19.5%~20.5%粗蛋白质水平可改善胴体性状,18.5%粗蛋白质水平可调节脂代谢。根据二次曲线模型估测,建议此生长阶段竹丝鸡饲粮粗蛋白质水平为21.41%~21.83%,可获得最佳生长性能。

【Objective】The experiment was conducted to investigate the effects of dietary crude protein level on growth performance,carcass traits and serum biochemical indices of male Silky fowl during 26 to 45 days of age,to investigate the crude protein requirment of Silky fowl at this stage.【Method】162526-day-old male Silky fowl were assigned to 5 groups with 5 replicates per group and 65 chickens per replicate,dietary crude protein levels were 18.5%,19.5%,20.5%,21.5%and 22.5%,respectively.The experiment lasted for 20 days.Two chickens with close to the average body weight were selected from each replicate for slaughter on the day of the end of this experiment,serum and carcasses were collected for determining carcass traits and serum biochemical parameters.【Result】①Dietary crude protein level extremely significantly affected final body,average daily gain and F/G(P<0.01),and with crude protein level increasing,final body weight and average daily gain were increased linearly and quadratically(P<0.01),F/G was decreased linearly and quadratically(P<0.01).Dietary crude protein level had no significant effect on average daily feed intake and survival rate(P>0.05).②Dietary crude protein level significantly or extremely significantly affected carcass weight(P<0.01),half-eviscerated weight(P<0.01)and eviscerated weight(P<0.05),but had no significant effect on breast muscle rate,leg muscle rate and abdominal fat rate(P>0.05).With dietary crude protein level increasing,carcass weight and half-eviscerated weight were decreased linearly and quadratically(P<0.01 or P<0.05).③Dietary crude protein level extremely significantly affected the serum contents of IGF-1 and TC(P<0.01),and with dietary crude protein level increasing,the TC content was decreased linearly(P<0.05).Dietary crude protein level had no significant effects on contents of BUN and TG(P>0.05).【Conclusion】Dietary 21.5%crude protein level could improve growth performance,19.5%to 20.5%crude protein level could improve carcass traits and 18.5%crude protein level could regulate lipid metabolism.According to the estimation of quadratic curve model,it was suggested that dietary 21.41%to 21.83%crude protein could achieve the best growth performance at this stage.