日粮蛋白质水平及有机硒补给时间对肉鸡生长性能及肌肉硒沉积的影响

Effect of dietary protein level and time of supplementation with organic selenium on growth and retention of selenium in the muscle of broiler chickens

比较不同日粮蛋白质水平下硒补给时间对肉鸡生长性能及肌肉硒沉积的影响。选用288只1日龄AA，2×3因子随机设计进行试验。结果表明：日粮高蛋白质水平（美国NRC标准的105％）下肉鸡各阶段平均体重、日均耗料量均高于低蛋白水平（NRC标准）（P〈0．01），料肉比低于低蛋白质水平（P〈0．05）。低蛋白日粮提高了42日龄肉鸡胸肌硒含量（P〈0．01），对49日龄肌肉硒含量没有影响（P〉0．05）。0～6周龄低蛋白水平组死亡率较高蛋白水平组显著降低10．19％（P〈0．05）。有机硒补给时间对生长性能无显著影响（P〉0．05），但对肌肉中硒沉积影响显著（P〈0．01）：42日龄胸肌硒含量在全期补给组显著高于分阶段补给组，且后期补给显著高于前期补给，腿肌硒含量全期与后期补给无差异，但都显著高于前期补给组；49日龄胸腿肌硒含量全期补给有机硒组极显著高于后期补给组。高蛋白质日粮能有效提高肉鸡生长性能，但不利于肌肉中硒的沉积；持续补给硒较分阶段补给更能提高肌肉中硒的沉积量，后期补给同前期补给相比对肌肉硒沉积更有效。

The effects of time of supplementation with organic selenium （Se） on growth and selenium retention in muscles at different dietary protein levels （DPL） were investigated with 288 1-day-old male Abor Acre broiler chicks in a 2 × 3 factorial experiment. When we increased the DPL by 5%, the live body weight and daily feed intake increased but feed conversion ratio decreased significantly（ P〈0.05）. Lower DPL improved muscle selenium retention on the 42nd day（P〈0.01） ; however the retention was not influenced by DPL on the 49th day. Mortality in groups with lower dietary protein was 10.2% less （P〈0.05）during the first 6 weeks, compared with those fed with higher proteins. The time of supplementation with organic selenium had no obvious effect on growth（P〈0.05） but remarkably affected muscle selenium retention（P〈0.01）. Supplementation during the whole feeding period resulted in the highest Se retention in the breast muscle 42 days after treatment, and the retention in groups supplied during 4-6 weeks was higher than in those supplied during 0-3 weeks. There were no differences among groups in the amount of selenium in leg muscle during the whole period and 4-6 weeks, while both were much higher than during 0-3 weeks. On the 49th day, selenium retention in both breast and leg muscles in groups supplemented during the whole period was higher than in groups with phased-supplementation. These results indicated that higher protein level effectively increased growth but was not beneficial to selenium retention. Selenium supplementation during the whole growth period would result in its higher retention in breast and leg muscles than supplementation during 0-3 or 4-6 wk.