Zuidhof M J, Schneider B L, Carney V L, Korver D R, Robinson F E
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada T6G 2P5
Livestock Research Branch, Alberta Agriculture and Rural Development, Edmonton, AB, Canada T6H 5T6.
Poult Sci. 2014 Dec;93(12):2970-82. doi: 10.3382/ps.2014-04291. Epub 2014 Sep 26.
The effect of commercial selection on the growth, efficiency, and yield of broilers was studied using 2 University of Alberta Meat Control strains unselected since 1957 and 1978, and a commercial Ross 308 strain (2005). Mixed-sex chicks (n = 180 per strain) were placed into 4 replicate pens per strain, and grown on a current nutritional program to 56 d of age. Weekly front and side profile photographs of 8 birds per strain were collected. Growth rate, feed intake, and measures of feed efficiency including feed conversion ratio, residual feed intake, and residual maintenance energy requirements were characterized. A nonlinear mixed Gompertz growth model was used to predict BW and BW variation, useful for subsequent stochastic growth simulation. Dissections were conducted on 8 birds per strain semiweekly from 21 to 56 d of age to characterize allometric growth of pectoralis muscles, leg meat, abdominal fat pad, liver, gut, and heart. A novel nonlinear analysis of covariance was used to test the hypothesis that allometric growth patterns have changed as a result of commercial selection pressure. From 1957 to 2005, broiler growth increased by over 400%, with a concurrent 50% reduction in feed conversion ratio, corresponding to a compound annual rate of increase in 42 d live BW of 3.30%. Forty-two-day FCR decreased by 2.55% each year over the same 48-yr period. Pectoralis major growth potential increased, whereas abdominal fat decreased due to genetic selection pressure over the same time period. From 1957 to 2005, pectoralis minor yield at 42 d of age was 30% higher in males and 37% higher in females; pectoralis major yield increased by 79% in males and 85% in females. Over almost 50 yr of commercial quantitative genetic selection pressure, intended beneficial changes have been achieved. Unintended changes such as enhanced sexual dimorphism are likely inconsequential, though musculoskeletal, immune function, and parent stock management challenges may require additional attention in future selection programs.
利用自1957年和1978年以来未进行选育的2个阿尔伯塔大学肉用鸡对照品系以及一个商业罗斯308品系（2005年），研究了商业选育对肉鸡生长、效率和产量的影响。每个品系的混合性别雏鸡（n = 180）被放入每个品系4个重复栏中，并按照当前的营养方案饲养至56日龄。每周收集每个品系8只鸡的正面和侧面照片。对生长速率、采食量以及包括饲料转化率、剩余采食量和剩余维持能量需求在内的饲料效率指标进行了测定。使用非线性混合Gompertz生长模型预测体重和体重变化，这对后续的随机生长模拟很有用。从21日龄至56日龄，每隔一周对每个品系8只鸡进行解剖，以描述胸肌、腿部肌肉、腹部脂肪垫、肝脏、肠道和心脏的异速生长情况。采用一种新的非线性协方差分析来检验异速生长模式因商业选育压力而发生变化的假设。从1957年到2005年，肉鸡生长增加了400%以上 , 同时饲料转化率降低了50%，相当于42日龄活体重的年复合增长率为3.30%。在同一48年期间，42日龄的饲料转化率每年下降2.55%。由于同期的遗传选育压力，胸大肌生长潜力增加，而腹部脂肪减少。从1957年到2005年，42日龄时，雄性小胸肌产量提高了30%，雌性提高了37%；雄性胸大肌产量提高了79%，雌性提高了85%。在近50年的商业数量遗传选育压力下，实现了预期的有益变化。诸如性二态性增强等非预期变化可能无关紧要，不过在未来的选育计划中，肌肉骨骼、免疫功能和种鸡管理方面的挑战可能需要更多关注。
