Yuhao Wang ¹ Xinping Wang ² Yirong Wang ³ Fanli Kong ³ Songyu Liao ¹ Zhaxi Pubu ² Jiangcuo Silang ² Lixu Chai ² Siyue Zhao ^4*

• ¹ College of Water Conservancy and Hydropower, Sichuan Agricultural University, Ya'an, China
• ² Xizang Changdu Animal Husbandry Station, Changdu, China
• ³ College of Life Science, Sichuan Agricultural University, Ya'an, China
• ⁴ Sichuan Agricultural University, Ya'an, China

Tibetan Awang sheep (Ovis aries), indigenous to the Qinghai-Tibet Plateau, are highly adapted to high-altitude environment. However, knowledge regarding their gut bacterial composition remains limited. A comprehensive 16S rRNA high-throughput sequencing was performed on fecal samples from 15 Awang sheep under pure grazing, semi-captivity, and full captivity breeding models. Our results revealed that Firmicutes and Bacteroidetes were the most abundant bacterial phyla, while Christensenellaceae_R-7_group, Romboutsia, Rikenellaceae_RC9_gut_group, Ruminococcus, and Bacteroides were prevalent genera in the gut microbiota of Awang sheep. Meanwhile, the predominant presence of Bacteroides with increasing altitude of breeding locations indirectly demonstrates its crucial role in mediating energy acquisition among Awang sheep at high altitudes. Furthermore, PCoA and ANOSIM analysis exhibited significant differences in bacterial composition across all breeding models (r > 0.6, p < 0.001). Christensenellaceae_R-7_group, Romboutsia, and Ruminococcus were significantly abundant in the pure grazing breeding model, while Rikenellaceae_RC9_gut_group and Bacteroides were more abundant in the semi-captivity breeding model. An abnormally high abundance of Acinetobacter indicated a potential risk of Acinetobacter infection in the fully captive group. The environmental association analysis exhibited that meadows diet (R 2 = 0.938, Pr[>r] = 0.001) and altitude (R 2 = 0.892, Pr[>r] = 0.001) had significant effects on the dominant genera, explaining a substantial proportion of the total variation in community composition. PICRUSt predictions revealed potential functional differences among the microbiota, with changes in metabolic pathways, signal transduction and transport systems across the different breeding models. The present findings provide insights into the microbiota dynamics of Awang sheep and offer guidance for their scientific husbandry management.