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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (5): 169-177.DOI: 10.11686/cyxb2021091

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Effects of different concentrate supplement levels on rumen fermentation and microbial community structure of grazing yaks in the warm season

Dong-wen DAI1,2,3(), Kai-yue Pang1,2,3(), xun WANG1,2,3, Ying-kui YANG1,2,3, Sha-tuo CHAI1,2,3(), Shu-xiang WANG1,2,3()   

  1. 1.Academy of Animal Husbandry and Veterinary Sciences,Qinghai University,Xining 810016,China
    2.Key Laboratory of Plateau Grazing Animal Nutrition and Feed Science of Qinghai Province,Xining 810016,China
    3.Yak Engineering Technology Research Center of Qinghai Province,Xining 810016,China
  • Received:2021-03-15 Revised:2021-07-12 Online:2022-05-20 Published:2022-03-30
  • Contact: Sha-tuo CHAI,Shu-xiang WANG

Abstract:

The aim of this research was to investigate the effects of different concentrate supplement levels on rumen fermentation and the rumen microbial community structure of grazing yaks in the warm season. Forty-eight male yaks with good body condition and similar body weight were randomly assigned to four groups (n=12). Yaks in the control group were only grazed, while the three supplement groups received 0.5 (Ⅰ), 1.5 (Ⅱ), and 2.5 kg·d-1 (Ⅲ) of concentrate, respectively. There was a 10-day pre-test period and the experimental period lasted 60 days. The experiment results showed that: 1) As concentrate supplementation level increased, the concentration of ruminal fluid total volatile fatty acids, propionic acid, butyric acid, isobutyric acid, valeric acid and isovaleric acid increased quadratically (P<0.05), while ruminal pH, concentration of acetic acid and the acetic∶propionic acid ratio decreased quadratically (P<0.05) and the concentration of microbial protein in supplement groups Ⅱ and Ⅲ were significantly higher than those in the other two groups. 2) In total, 3138 operational taxonomic units (OTUs) were detected, and 1337 of those OTUs (42.61% of the total OTUs) were shared by all four treatment groups. The control treatment had 183 unique OTUs, while group Ⅲ had 106 unique OTUs. The number of microbial species, Chao1 index and Shannon index decreased with increasing concentrate supplementation level (P<0.05). 3) At the phylum level, with increasing concentrate supplementation level, the relative abundance of Bacteroidetes increased quadratically (P<0.05), while the relative abundance of Firmicutes decreased quadratically (P<0.05) and the relative abundance of Actinobacteria increased linearly (P<0.05). At the genus level, with increased concentrate supplementation level, the relative abundances of Prevotella_1, Christensenellaceae_R-7 and Prevotellaceae_UCG-001 increased quadratically (P<0.05), while relative abundance of Succiniclasticum andRuminococcaceae_UCG-005 decreased quadratically (P<0.05). In conclusion, increasing the level of concentrate supplementation promoted rumen fermentation and increased the abundance of the some starch-degrading bacteria of grazing yaks in the warm season.

Key words: grazing yaks, concentrate supplementation level, rumen fermentation, rumen microbial community structure