The British Ixworth: individual growth and egg production of a purebred dual-purpose chicken

1. Killing male one-day-old chicks, especially from layer lines, is banned in some European countries. Therefore, dual-purpose chickens, where each sex is used for meat and egg production, respectively, offer an alternative production solution. This study evaluated the British purebred breed Ixworth as a dual-purpose chicken for meat and egg production. 2. Ixworth chicks (<i>n</i> = 167) were hatched and reared mixed-sex in a floor housing system, with two groups receiving a commercial pullet diet (treatment 1) and two groups receiving a diet composed for males of layer lines (treatment 2). Individual chick performance data were recorded. Males were slaughtered at 12 weeks of age, and their growth rate and carcase variables were analysed. All hens were continuously reared on the pullet diet and kept in a free-range system from 20 weeks old for one laying period (52 weeks). In addition, group-based feed consumption and mortality were recorded. 3. Cockerels in treatment 1 and 2 showed significantly different [T(88) = −2.846, <i>P</i> = 0.003] growth rates (25.3 <i>vs</i>. 27.4 g/day) and average final weights (2166 g <i>vs</i>. 2344 g). The hens in treatment 1 (<i>n</i> = 41) laid an average of 193 eggs per hen housed (mean egg weight: 56.9 g), whereas those in treatment 2 (<i>n</i> = 35) laid 195 eggs per hen housed (mean egg weight: 56.5 g). Nest acceptance was &gt;97.5% and feed consumption was up to 140 g/bird/day. 4. The results showed that the Ixworth may be a suitable breed for dual-purpose use and could be improved through selective breeding, offering potential for preservation of this local breed as well as general biodiversity in poultry farming.

1. 部分欧洲国家已明令禁止宰杀一日龄雄性雏鸡，尤以蛋鸡品系的雏鸡为甚。据此，肉蛋兼用型鸡（dual-purpose chickens）——即雌雄个体分别用于肉用与蛋用生产——为养殖业提供了可行的替代方案。本研究针对英国纯种Ixworth鸡开展评估，验证其作为肉蛋兼用型鸡的生产性能。
2. 本研究共孵化并饲养167羽Ixworth混性别雏鸡，采用地面养殖模式，将其分为两组饲喂商品后备母鸡日粮（处理组1），另外两组饲喂蛋鸡品系公鸡专用日粮（处理组2），并记录每羽雏鸡的生长性能数据。雏鸡饲养至12周龄时屠宰公鸡，分析其生长速率与屠体性状指标。所有母鸡均全程饲喂后备母鸡日粮，并于20周龄起转入散养系统开展为期52周的一个产蛋周期。此外，本研究还记录了群体采食量与死亡率数据。
3. 处理组1与处理组2的青年公鸡生长速率存在显著差异[T(88) = −2.846, P = 0.003]，分别为25.3 g/天与27.4 g/天，平均终体重分别为2166 g与2344 g。处理组1的母鸡（n = 41）每羽入舍母鸡平均产蛋193枚，平均蛋重56.9 g；而处理组2的母鸡（n = 35）每羽入舍母鸡平均产蛋195枚，平均蛋重56.5 g。产蛋窝利用率超过97.5%，日均采食量可达140 g/羽。
4. 研究结果表明，Ixworth鸡是一种适宜的肉蛋兼用型品种，且可通过选择性育种进行性能改良，这为该地方品种的保种以及家禽养殖领域的生物多样性保护提供了潜在可能。