Comparison of Cold and Warm Water Intake in Winter on Growth Performance, Thermoregulation, Rumen Fermentation Parameters, and Microflora of Wandong Bulls (Bos taurus)

Efficient farm practices are crucial for livestock health and performance, and cold stress is a major challenge for cattle in winter. This study aimed to investigate the effects of cold and warm water in winter on growth performance, thermal stress indicators, serum hormones and metabolites, rumen fermentation parameters, rumen fiber degrading enzyme and rumen microflora of yellow cattle during winter. Eight Wandong Bulls (Bos taurus) were divided into two groups: group C, which received cold water (6.36 ± 1.99 °C) and group E, which received warm water (32.00 ± 3.12 °C) for 30 d. Results showed that warm-water intake significantly increased ADG (p = 0.024) and DMI (p = 0.046), and decreased (p = 0.047) the ratio of feed intake to weight gain. Furthermore, the heat production, respiratory rate, surface temperature and rectal temperature of cattle did not alter varying with water temperature, but the heat production value of bulls increased (29.64 vs 25.76 MJ/W0.75 h-1) by cold-water intake compared to warm water. The concentrations of thyroxine (p = 0.021), serum urea nitrogen (p = 0.025), and glucose (p = 0.011) increased with bulls drinking cold water compared to warm water. The concentrations of NH3-N (p = 0.048), total VFA (p = 0.010), acetate (p = 0.009), propionate (p = 0.009), cellulase (p < 0.01) and xylanase (p < 0.05) were lower in group C compared to group E. The total bacterial abundance, as well as specific species including Ruminococcus flavus, Ruminococcus albus, and Prevotella ruminicola, were lower (p < 0.05) in group C compared to group E. In conclusion, in comparison with cold water, drinking warm water during the winter enhanced growth performance by influencing energy metabolism, regulating serum hormones and metabolites, and modulating ruminal microflora of bulls.