Effects of Fermented Manure Bedding Thickness on Bulls’ Growth, Behavior, and Welfare as Well as Barn Gases Concentration in the Barn

SIMPLE SUMMARY: Due to the increasing cost of common bedding materials, there is a growing preference for recycled manure solids as bedding materials. This study aimed to evaluate bull growth performance, behavior, and animal welfare, and gases concentration in the barn under different thicknesses of bedding. Our results indicated that deep fermented bedding promoted the growth and welfare of bulls. The results showed that soft fermented bedding played a positive role in the growth and development of bulls, and it increased the feed conversion rate (F/G, ratio of feed to gain), and the effect of deep fermented bedding was better than the shallow one. The results indicated that the DFB (deep fermented bedding) group exhibited optimal hoof health, body hygiene, and lying time, followed by the SFB (shallow fermented bedding) group and the CF (concrete floor) group. As for the gases concentration, the contents of ammonia and carbon dioxide were the lowest in the DFB group, followed by the SFB group, and they were the highest in the CF group at the same time points. In summary, fermented manure bedding significantly improves the growth performances, behavior, and welfare of bulls as well as gases concentration in the barn, and the improvement effect achieved by deep fermented bedding is more obvious than by shallow fermented bedding. ABSTRACT: Providing clean, comfortable bedding is essential for the growth and welfare of bulls. This study was aimed to investigate the effects of bedding thickness on growth performance, behavior, and welfare of bulls as well as gases concentration in the barn. Thirty-six healthy Simmental bulls (7–9 months old) were randomly divided into three groups and raised on 0 cm (concrete floor, CF), 15 cm (shallow fermented bedding, SFB), and 30 cm (deep fermented bedding, DFB) fermented manure bedding. The results showed that the DFB group exhibited the optimal ADG (average daily gain), F/G (ratio of feed to gain), hoof health, body hygiene, and lying time, followed by the SFB group and the CF group (p < 0.05). As for the barn gas environment, the contents of ammonia and carbon dioxide were the lowest in the DFB group, followed by the SFB group, and they were the highest in the CF group at the same time points (p < 0.01). In summary, fermented manure bedding significantly improves the growth performances, behavior, and welfare of bulls as well as gases concentration, and the improvement effect achieved by deep fermented bedding is more obvious than by shallow fermented bedding.