The aim of this study was to evaluate the effect of production system on the health, performance, carcass characteristics, and meat quality of autumn born (AB) and spring born (SB) Holstein bulls. The study involved a total of 224 Holstein bulls and was conducted over two years (2017/18, 2018/19). The four production system treatments differed during the grower period and consisted of: (i) grazed with no concentrate supplementation (G), (ii) grazed with 2 kg concentrate supplementation per day (G2), (iii) grazed with ad libitum access to concentrates (GA) and (iv) housed with ad libitum access to concentrates and grass silage (HA). All bulls were finished on ad libitum concentrates and grass silage and were slaughtered at a mean age of 15.5 months. Total grower dry matter intake (DMI) (p < 0.001) and total finishing DMI (p < 0.001) differed between production systems for both AB and SB bulls, with that of GA bulls being the greatest in both cases. Average daily gain (ADG) during the grower period was greatest (p < 0.001) for the HA production system in the AB bulls and the GA and HA production systems for the SB bulls. However, during the finishing period, G bulls had the greatest (p < 0.001) ADG of the AB bulls, while that of the SB bulls was from the G2 production system (p < 0.001). For both AB and SB, bulls on the GA and HA production systems produced heavier cold carcass weights than the G and G2 bulls (p < 0.001). There was no significant difference (p > 0.05) in health, carcass conformation, fat classification, or meat quality between production systems.

中文翻译：

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牛肉生产系统对荷斯坦公牛健康、生产性能、胴体特性和肉质的影响


本研究的目的是评估生产系统对秋季出生（AB）和春季出生（SB）荷斯坦公牛的健康、生产性能、胴体特性和肉质的影响。该研究共涉及 224 头荷斯坦公牛，历时两年（2017/18、2018/19）。四种生产系统处理在生长期间有所不同，包括：(i) 不补充精料的放牧 (G)，(ii) 每天补充 2 kg 精料的放牧 (G2)，(iii) 自由采食的放牧浓缩物（GA）和（iv）可随意获取浓缩物和青贮饲料（HA）。所有公牛均自由采食浓缩物和青贮饲料，并在平均 15.5 个月大时屠宰。 AB 和 SB 公牛的生产系统之间的种植者干物质总摄入量 (DMI) ( p < 0.001) 和育肥总 DMI ( p < 0.001) 有所不同，其中 GA 公牛在这两种情况下都是最大的。 AB 公牛的 HA 生产系统和 SB 公牛的 GA 和 HA 生产系统在生长期间的平均日增重 (ADG) 最大 ( p < 0.001)。然而，在育肥期，G 公牛的 ADG 比 AB 公牛最大 ( p < 0.001)，而 SB 公牛的 ADG 来自 G2 生产系统 ( p < 0.001)。对于 AB 和 SB，GA 和 HA 生产系统的公牛生产的冷胴体重量比 G 和 G2 公牛重 ( p < 0.001)。生产系统之间的健康状况、胴体形态、脂肪分类或肉质没有显着差异（ p > 0.05）。