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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (2): 182-191.DOI: 10.11686/cyxb2020545

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Effects of dietary protein levels on ruminal fungal community structure and function in Tibetan sheep

Xun-gang WANG1(), Xiao-ling ZHANG1,2, Tian-wei XU1, Yuan-yue GENG1,2, Lin-yong HU1, Na ZHAO1, Hong-jin LIU1, Sheng-ping KANG1,2, Shi-xiao XU1()   

  1. 1.Northwest Institute of Plateau Biology,Chinese Academy of Sciences,Xining 810008,China
    2.University of Chinese Academy of Sciences,Beijing 100049,China
  • Received:2020-12-08 Revised:2021-03-04 Online:2022-02-20 Published:2021-12-22
  • Contact: Shi-xiao XU

Abstract:

This study aimed to investigate the effects of dietary protein levels on ruminal fungal community structure and function of Tibetan sheep. A total of eighteen 12-month-old, healthy, castrated Tibetan sheep with similar initial body weights (31.71±0.72) kg were randomly divided into three treatment groups, with 6 sheep in each group. During the whole experiment, the sheep were fed diets with low, medium or high dietary crude protein (CP) levels (LP group, 10.06%CP; MP group, 12.10%CP; HP group, 14.12%CP) and similar metabolizable energy. The experiment took place over 120 d with a 15 d adaptation period and 105 d measurement period. It was found that: 1) The final body weights, average daily gains, and average daily feed intake of the LP group were lower than those in MP and HP groups (P<0.05), while the feed conversion ratio in LP was higher than that in MP and HP groups (P<0.05). 2) A total of 1547415 clean gene tags were obtained from 18 samples, and the total number of OTUs detected by a cluster analysis was 4073. The diversity index of the rumen fungi in Tibetan sheep was not significantly (P>0.05) affected by the dietary protein levels. 3) At the phylum level, the most dominant fungal phyla from the ruminal samples were Ascomycota, Basidiomycota, Mortierellomycota and Neocallimastigomycota. At the genus level, PenicilliumAcauliunCladosporiumFusarium and Alternaria were detected as highly abundant taxa in the rumen. 4) A total of 33 biomarkers were identified at various taxonomic levels based on linear discriminant effect size analysis (LEfSe). 5) The main function of the rumen fungal flora, as predicted by FUNGuid, was saprophytic activity. In summary, higher dietary protein levels significantly improved daily weight gain of Tibetan sheep, but had no significant effect on microbial diversity and community structure.

Key words: protein, Tibetan sheep, growth performance, rumen, ruminal fungi