Effects of Heated Drinking Water during the Cold Season on Serum Biochemistry, Ruminal Fermentation, Bacterial Community, and Metabolome of Beef Cattle

This study explored the effects of drinking heated water in the cold seasons on the serum metabolism, rumen microbial fermentation, and metabolome of beef cattle. Twelve fattening cattle (642 ± 14.6 kg) aged 21 to 22 months were randomly and equally divided into two groups based on body weight: one receiving room-temperature water (RTW; average 4.39 ± 2.55 °C) and the other heated water (HW; average 26.3 ± 1.70 °C). The HW group displayed a significant decrease in serum glucose (p < 0.01) and non-esterified fatty acid (p < 0.01), but increases in insulin (p = 0.04) and high-density lipoprotein (p = 0.03). The rumen fermentation parameters of the HW group showed substantial elevations in acetate (p = 0.04), propionate (p < 0.01), isobutyrate (p = 0.02), and total volatile fatty acids (p < 0.01). Distinct bacterial composition differences were found between RTW and HW at the operational taxonomic unit (OTU) level (R = 0.20, p = 0.01). Compared to RTW, the HW mainly had a higher relative abundance of Firmicutes (p = 0.07) at the phylum level and had a lower abundance of Prevotella (p < 0.01), norank_f_p-215-o5 (p = 0.03), and a higher abundance of NK4A214_group (p = 0.01) and Lachnospiraceae_NK3A20_group (p = 0.05) at the genus level. In addition, NK4A214_group and Lachnospiraceae_NK3A20_group were significantly positively correlated with the rumen propionate and isovalerate (r > 0.63, p < 0.05). Prevotella was negatively correlated with rumen propionate and total volatile fatty acids (r = −0.61, p < 0.05). In terms of the main differential metabolites, compared to the RTW group, the expression of Cynaroside A, N-acetyl-L-glutamic acid, N-acetyl-L-glutamate-5-semialdehyde, and Pantothenic acid was significantly upregulated in HW. The differentially regulated metabolic pathways were primarily enriched in nitrogen metabolism, arginine biosynthesis, and linoleic acid metabolism. Prevotella was significantly positively correlated with suberic acid and [6]-Gingerdiol 3,5-diacetate (r > 0.59, p < 0.05) and was negatively correlated with Pantothenic acid and isoleucyl-aspartate (r < −0.65, p < 0.05). NK4A214_group was positively correlated with L-Methionine and glycylproline (r > 0.57, p < 0.05). Overall, our research demonstrates the important relationship between drinking water temperature and metabolic and physiological responses in beef cattle. Heating drinking water during cold seasons plays a pivotal role in modulating internal energy processes. These findings underscore the potential benefits of using heated water as a strategic approach to optimize energy utilization in beef cattle during the cold seasons.