The Effect of Beef Production System on the Health, Performance, Carcass Characteristics, and Meat Quality of Holstein Bulls

SIMPLE SUMMARY: Dairy-origin beef accounts for a considerable proportion of the prime beef supply. Yet, the beef production potential of dairy bred calves is declining following years of single trait selection for attributes such as milk yield. Producing these animals as bulls allows for increased growth rates and efficiency in comparison to steers, however these systems often involve a high level of concentrate feeding. Thus, creating a system that is subject to fluctuating feed prices and beef market volatility. This objective of this study was to evaluate four production systems, which differed in terms of diet during the grower period. The impacts on health, performance, carcass characteristics, and meat quality were all considered. Our research shows that ad libitum concentrate feeding throughout the production system resulted in superior carcass weights. Increasing the proportion of grazed grass in the diet during the grower period, did result in a reduced carcass weight in comparison to ad libitum concentrates, however total concentrate intake, and therefore the production costs during the grower period were also reduced. Production system had no effect on health or meat quality. In conclusion, including a gazing period within bull beef production systems may be a more sustainable approach to producing Holstein bulls. ABSTRACT: 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.