Consumer concern for broiler welfare has increased interest in chicken from slower growing (SG) broiler strains. Broilers from SG strains take longer to reach market weight, which may necessitate differences in management practices, such as stocking density. This study evaluated the effects of 2 stocking densities on production performance, body conformation, and welfare of broilers from 2 strains. Broilers from strains that reach market weight at age 42 D (CONV; N = 284) and at 63 D (SG; N = 284) were exclusively stocked into pens at a density of either 29 kg/m2 or 37 kg/m2. Birds were provided the same starter, grower, and finisher diets with diet phase changes occurring when SG bird body weight (BW) matched CONV. Live BW, body length, pelvic width, shank length, shank width, keel length, breast width, and breast depth were collected at 4 phases: Phase 1-chick placement, Phase 2-starter, Phase 3-grower, and Phase 4-finisher. At Phase 4, footpad dermatitis (FPD), hock burn (HB), and toe damage (TD) were scored. Feed conversion ratio (FCR) and mortality for each pen were recorded throughout the study. Final BW was similar (2.68 kg) for both strains and stocking densities of birds (P > 0.05). CONV bird FCR was 35% more efficient than SG (P < 0.0001). CONV birds had shorter bodies and shanks compared with SG birds at Phases 3 and 4 (P < 0.05). Slower growing birds stocked at 37 kg/m2 had the longest bodies and keel bones at Phase 4 (P < 0.01). Also at Phase 4, SG birds stocked at 29 kg/m2 had the lowest prevalence of HB (4%), yet the highest prevalence of TD (28%; P < 0.01). These results indicate differences in the effects of strain and stocking density on male broiler conformation, performance, and welfare and highlight the importance of tailoring management practices to the strain of broiler raised.

中文翻译：

---

以2种放养密度饲养的常规和慢速生长的肉鸡的性能，身体形态和福利方面的差异。

消费者对肉鸡福利的关注增加了生长缓慢（SG）的肉鸡菌株对鸡肉的兴趣。SG菌株的肉鸡需要更长的时间才能达到市场重量，这可能需要不同的管理方法，例如放养密度。这项研究评估了两种放养密度对两种菌株对肉鸡生产性能，身体形态和福利的影响。来自在42 D（CONV; N = 284）和63 D（SG; N = 284）达到市场重量的品系的肉鸡专门以29 kg / m2或37 kg / m2的密度放养到围栏中。当SG鸟的体重（BW）与CONV相匹配时，向鸟提供相同的开始，生长和结束日粮，并且饮食阶段发生变化。在以下四个阶段收集活体体重，体长，骨盆宽度，小腿长度，小腿宽度，龙骨长度，乳房宽度和乳房深度：第1阶段的小鸡放置，第2阶段的启动器，第3阶段的种植者和第4阶段的完成者。在第4阶段，对脚垫皮炎（FPD），飞节烧伤（HB）和脚趾损伤（TD）进行了评分。在整个研究过程中记录每只钢笔的饲料转化率（FCR）和死亡率。品系和家禽密度的最终体重相似（2.68 kg）（P> 0.05）。CONV禽类FCR的效率比SG高35％（P <0.0001）。CONV鸟的身体和小腿短于第3和第4阶段的SG鸟（P <0.05）。在第4阶段，以37 kg / m2饲养的生长较慢的禽类的身体和龙骨最长（P <0.01）。同样在第4阶段，以29 kg / m2饲养的SG禽的HB患病率最低（4％），但TD患病率最高（28％； P <0.01）。