Abstract
Air temperature and relative humidity (RH) are 2 important climatic elements that affect animal welfare and health. The prevailing hot and humid or dry climate is one of the major constraints for optimum poultry production, especially in the tropics and subtropical regions. Many studies have suggested that exposure to hot-humid or dry climate is associated with a high risk of metabolic imbalance; however, the underlying metabolic changes caused by low or high RH climate is not yet well understood. Therefore, we used a comprehensive ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry-based metabolic profiling of fecal samples to explore the effects of hot-humid and dry climate on metabolic pathways in broilers. A total of 180 twenty-eight-day-old Arbor Acres broilers were randomly allocated to 3 treatments, each containing 6 replicates of 10 birds per treatment, using a completely randomized design. Birds were reared at 35, 60, or 85% RH at 32°C (temperature increased by 3°C every 3 d from 20°C to 32°C within 15 d: 20°C, 23°C, 26°C, 29°C, 32°C) for 15 d. Results showed that significant changes in the levels of 36 metabolites were detected. Evidence of changes in gluconeogenesis associated to pyruvate metabolism, galactose metabolism, and ABC transporter was observed. In addition, hot-humid and dry stress also affected the protein translation process caused by aminoacyl-tRNA biosynthesis, which may be associated with protein synthesis and hormone secretion disorders. Furthermore, we observed significant changes in primary bile acid biosynthesis and taurine and hypotaurine metabolism, which indicated that fat synthesis was affected. We also observed significant changes in arginine and proline metabolism and histidine metabolism, which were associated with skin vasodilation and blood flow. These results provide biochemical insights into metabolic changes due to hot-humid or dry climate.