Ecological and Functional Changes in the Hindgut Microbiome of Holstein Cows at High Altitudes.

The extreme environmental conditions of the Qinhai-Tibetan Plateau (QTP) challenge livestock survival and productivity, yet little is known about how high-altitude environments impact the gut microbiota of dairy cows. To fill this gap, we systematically investigated the differences in the hindgut microbiome between 87 plateau Holstein cows and 72 plain Holstein cows using 16S rRNA gene sequencing. Our analysis revealed that the hindgut microbiota of the plateau group exhibited lower species richness but higher evenness than that in the plain group. Additionally, significant separation in hindgut microbiota composition between the two groups was observed based on altitude, while parity, days in milk, and age did not show a comparable impact. Moreover, altitude had a lasting impact on bacterial communities and their co-occurrence networks, resulting in reduced microbial interactions and lower modularity in the plateau group. Furthermore, we identified four key microbial taxa, the and families, as well as the and genera, which were associated with the regulation of carbohydrate digestion and energy metabolism and might help the Holstein cows adapt to the plateau environment. Our findings provide insights into strategies for enhancing the adaptability of dairy cows to high-altitude environments through microbiota modulation, which could ultimately contribute to improving livestock management and sustainability in these extreme environments.