Whole-genome analyses reveal selective signals in four Xinjiang cattle breeds

Xinjiang is home to three indigenous cattle breeds (Xinjiang Mongolian, Altay white-headed, and Kazakh cattle) and one crossbreed (Xinjiang Brown cattle), each possessing distinct and remarkable characteristics. In this study, we conducted comprehensive genome analyses of these four breeds in comparison with eight representative cattle breeds from around the world. Despite being predominantly Bos taurus, the proportion of Bos indicus ancestry in these indigenous breeds decreases with increasing latitude. This mixed genomic composition contributes to higher nucleotide diversity, lower linkage disequilibrium, and larger effective population sizes. Notably, Xinjiang Brown cattle exhibited higher LD at short distances, faster LD decay, and the largest effective population size, indicative of hybrid characteristics. Furthermore, we identified selective signals for lipids dynamics and coat colour in Altay white-headed cattle, immune resistance to local pathogens in Kazakh cattle, hydro-electrolyte balance and immune response in Xinjiang Mongolian cattle, and rapid growth and large body size in Xinjiang Brown cattle, as well as substance metabolism in three indigenous cattle. Our findings not only deepen the understanding of breed origins and diversity but also provide a foundation for exploring the genetic mechanisms underlying breed characteristics and facilitating further breed improvement.