Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, P. R. China.
Poult Sci. 2009 Dec;88(12):2575-84. doi: 10.3382/ps.2009-00245.
A study was conducted to evaluate the effects of varying nutrient density with constant ME:CP ratio on growing performance, carcass characteristics, and blood responses in 2 distinct broiler breeds of male chickens (Arbor Acres, a commercial line, and Beijing-You, a Chinese nonimproved line). Experimental diets were formulated with high, medium, or low nutrient densities for 3 growing phases. Starter diets (1 to 21 d) contained 23, 21, and 19% CP with 3,059, 2,793, and 2,527 kcal/kg of ME; grower diets (22 to 35 d) contained 21, 19, and 17% CP with 3,150, 2,850, and 2,550 kcal/kg of ME; and finisher diets (36 to 42 d for Arbor Acres and 36 to 91 d for Beijing-You) had 19, 17, and 15% CP with 3,230, 2,890, and 2,550 kcal/kg of ME. Male hatchlings (216 of each breed) were randomly assigned to 6 replicates of 12 birds in each treatment. Arbor Acres broilers had better (P < 0.001) BW gain, feed conversion ratio (FCR), and carcass yield, but had greater (P < 0.001) abdominal and carcass fat deposition. In both breeds, the higher nutrient density increased (P < 0.05) BW gain, protein efficiency ratio, and energy efficiency ratio while decreasing (P < 0.05) feed intake and FCR. The breed differences were increased for FCR, protein efficiency ratio, and energy efficiency ratio in the starter period and decreased for carcass chemical composition, respectively, by higher nutrient density. These findings indicate that 1) genetic improvement has a significant effect on broiler responses to dietary nutrient density, 2) performance differences between breeds are lessened with diets of low nutrient density, 3) carcass quality differences are less when birds were fed diets of high nutrient density, 4) carcass composition is hardly modified by nutrient density and both breeds exhibit similar metabolite responses to dietary concentrations, and 5) optimal diets are deduced for these breeds for the 3 growing phases.
一项研究旨在评估在 ME:CP 比恒定的情况下，不同营养密度对 2 种不同肉鸡品种（阿伯拉考尔，商业品种和北京油鸡，中国非改良品种）生长性能、胴体特征和血液反应的影响。实验日粮在 3 个生长阶段分别用高、中、低营养密度配制。育雏期（1 至 21 天）饲料的 CP 含量分别为 23%、21%和 19%，ME 含量分别为 3059、2793 和 2527 千卡/千克；生长期（22 至 35 天）饲料的 CP 含量分别为 21%、19%和 17%，ME 含量分别为 3150、2850 和 2550 千卡/千克；育肥期（阿伯拉考尔的 36 至 42 天和北京油鸡的 36 至 91 天）饲料的 CP 含量分别为 19%、17%和 15%，ME 含量分别为 3230、2890 和 2550 千卡/千克。每个品种的 216 只雄性雏鸡随机分配到 6 个处理组，每组 12 只鸡。阿伯拉考尔肉鸡的 BW 增重、饲料转化率（FCR）和胴体产率更好（P < 0.001），但腹部和胴体脂肪沉积更高（P < 0.001）。在这两个品种中，较高的营养密度增加了（P < 0.05）BW 增重、蛋白质效率比和能量效率比，同时降低了（P < 0.05）饲料摄入量和 FCR。较高的营养密度增加了 starter 期 FCR、蛋白质效率比和能量效率比的品种差异，降低了 carcass 化学成分的品种差异。这些发现表明：1）遗传改良对肉鸡对日粮营养密度的反应有显著影响；2）低营养密度日粮可减少品种间的性能差异；3）高营养密度日粮饲养的鸡胴体质量差异较小；4）营养密度对胴体成分几乎没有影响，两种品种对日粮浓度的代谢物反应相似；5）为这两个品种推导了 3 个生长阶段的最佳日粮。
