Cattle are raised around the world and are frequently exposed to heat stress, whether in tropical countries or in regions with temperate climates. It is universally acknowledged that compared to those in temperate areas, the cattle breeds developed in tropical and subtropical areas have better heat tolerance. However, the underlying mechanism of heat tolerance has not been fully studied, especially from the perspective of intestinal microbiomics. The present study collected fecal samples of cattle from four representative climatic regions of China, namely, the mesotemperate (HLJ), warm temperate (SD), subtropical (HK), and tropical (SS) regions. Then, the feces were analyzed using high-throughput 16S rRNA sequencing. The results showed that with increasing climatic temperature from HLJ to SS, the abundance of Firmicutes increased, accompanied by an increasing Firmicutes to Bacteroidota ratio. Proteobacteria showed a trend of reduction from HLJ to SS. Patescibacteria, Chloroflexi, and Actinobacteriota were particularly highest in SS for adapting to the tropical environment. The microbial phenotype in the tropics was characterized by an increase in Gram-positive bacteria and a decrease in Gram-negative bacteria, aerobic bacteria, and the forming of_biofilms. Consistently, the functional abundances of organismal systems and metabolism were decreased to reduce the material and energy demands in a hot environment. Genetic information processing and information storage and processing may be how gut flora deals with hot conditions. The present study revealed the differences in the structure and function of gut microbes of cattle from mesotemperate to tropical climates and provided an important reference for future research on the mechanism of heat tolerance regulated by the gut microbiota and a potential microbiota-based target to alleviate heat stress.

The Xinglong buffalo is a local swamp buffalo breed adapted to tropical regions in China. To facilitate the protection and utilization of valuable genetic resources, we first developed the breed-specific single nucleotide polymorphism (SNP) liquid-phase chip based on genotyping-by-target-sequencing (GBTS) technology. Whole-genome resequencing data from 143 buffaloes, resulting in 34,757,694 SNPs, were used to identify 1208 breed-specific and 2889 background sites. This chip also incorporates 965 functional SNP sites derived from literature, including SNPs significantly associated with immunity, reproduction, growth, and production. A total of 5062 SNP sites were successfully identified for the development of a 5K liquid-phase genome-wide breeding chip for the Xinglong buffalo. The validation of the chip using 93 samples showed a high detection rate with good repeatability and consistency. In addition, the chip exhibits strong capabilities in clustering and kinship analysis. Results of kinship analysis underscored the importance of a breed-specific chip for the Xinglong buffalo. These results highlight the advantages of a low-density, cost-effective, and breed-specific SNP chip for accurate genotyping. This chip will support future endeavors in molecular breeding, conservation, and genetic evaluation of Xinglong buffalo, thereby facilitating the sustainable utilization of this valuable indigenous germplasm resource.