Yak rumen microbial diversity at different forage growth stages of an alpine meadow on the Qinghai-Tibet Plateau

Abstract

The rumen microbiota of ruminants plays a vital role in fiber digestion, and environmental factors affect its community structure. The yak (Bos grunniens) is the main livestock species that inhabits the Qinghai-Tibet Plateau (QTP) at regions located at high-altitude of 3,000–5,000 m. This work investigated the rumen bacterial community of yak that grazed on the QTP during the whole year to evaluate the relationship between the rumen bacterial community and the nutrient composition of forage plant at three stages. In this study, the diversity of the rumen prokaryotic community composition was monitored in 10 full-grazing yak in an alpine meadow of the QTP. The nutrient composition of three forage growth stages was determined: re-green stage (REGY), grassy stage (GY), and withered stage (WGY). High-throughput sequencing of bacterial 16S rRNA gene was used. The results showed that the nutritive composition of the alpine meadow changed with the seasons: crude protein (CP) (13.22%) was high in forage during REGY (spring), while neutral detergent fiber (NDF) (59.00%) was high during WGY (winter). Microbial diversity and richness were highest during REGY and the average number of operational taxonomic units from 30 samples was 4,470. The microbial composition was dominated by members of Bacteroidetes (51.82%), followed by Firmicutes (34.08%), and the relative microbial abundance changed in the three forage growth stages. Unweighted UniFrac distance PcoA showed that the bacterial community structure differed between REGY, GY, and WGY. Furthermore, taxonomic groups did not present differences regarding gender in these three stages. The rumen microbiota was enriched with functional potentials that were related to ABC transporters, the two-component system, Aminoacyl-tRNA biosynthesis, and metabolism of Purine, Pyrimidine, Starch and sucrose metabolism. Significant differences were found in the composition, diversity, and function of yak ruminal microorganisms during different forage growth stages. This indicates that microbial changes in the rumen depend on changes in the forage nutritional composition. These findings provide evidence on the rumen microbial diversity of yaks in the QTP.

Host and altitude factors affect rumen bacteria in cattle

“…Compared with lowaltitude vegetation types, the number of ruminant bacteria in the rumen of high-altitude grazing animals increased, and the acetic acid ratio decreased [24]. The results showed that the changes of rumen microorganisms in high-altitude animals were influenced by vegetative nutrients [25]. Compared with plain animals, intestinal microbes in high altitude were different and played more efficient roles.…”

Astragalus root extract improved average daily gain, immunity, antioxidant status and ruminal microbiota of early weaned yak calves

“…The ARE supplementation increased the abundance of Firmicutes , Proteobacteria and Actinobacteria , but decreased the abundance of Bacteroidetes . Rumen Proteobacteria has been shown to be correlated positively with NDF and ether extract metabolism in yak, 54 while Actinobacteria are not common in the rumen, but are common in soil microbiome 55 . In addition, Actinobacteria could use polysaccharides as nutritional sources, 56 and can inhabit the animal as pathogens such as, Corynebacterium , Mycobacterium , and Nocardia species and produce microbial bioactive natural products, such as antibiotics, chemotherapeutics, immunosuppressants and anthelmintics 9,57 .…”

Tibetan Sheep Adapt to Plant Phenology in Alpine Meadows by Changing Rumen Microbial Community Structure and Function

“…The herbage collection methods used in this study were similar to those reported by Ma et al (2019). Briefly, 10 quadrats (50 cm × 50 cm), with a distance between plots of more than 10 m, were randomly placed in the alpine meadow and the aboveground biomass was collected at each phenological period.…”

“…The growth of TS has changed due to grazing on natural grassland in different phenological periods, and it is therefore questionable whether the rumen microbiota has changed. To some extent, rumen microbial communities are only temporarily stable (Jami et al, 2013), and they will change with time (Ma et al, 2019), environment (Pitta et al, 2014) and host genetic factors (Han et al, 2020). These factors change the composition and structures of rumen microbial communities, but the functioning of the microbiome may or may not change.…”