Shenhe Liu

Abstract The gut microbiota, as the “second genome” of the human body, plays a central regulatory role in maintaining host physiological homeostasis; conversely, its dysbiosis can impair male reproductive function via the “gut-testis axis”, leading to a series of pathological manifestations such as abnormal semen quality, sexual dysfunction, and reproductive organ damage.

1. Introduction Yaks (Bos grunniens) are domesticated on the Qinghai-Tibetan Plateau with a population of 17.6 million, and play an essential role in the life of the local herdsman by providing different types of material such as milk, meat, manure, wool, and hide (1). Most of the yak population are in the Sichuan, Tibet, and Qinghai provinces of China and are domesticated under a traditional management system (2).