Effects of diets with different concentration-roughage ratios on the microbial community structure of Nubian goat rumen

The purpose of this study was to analyze the effects of diets with different concentration-roughage ratios on the microbial community structure of Nubian goat rumen. Thirty-six healthy Nubian ewes with similar body weights were randomly divided into three groups, with 12 goats per group. Goats in each group were fed total mixed rations with concentration-roughage ratios of 40∶60 (L), 50∶50 (M), or 60∶40 (H). The experimental period was 70 days. The results were as follows: 1) A total of 1901 OTUs were generated, of which 1348 OTUs were shared by the three groups, accounting for 70.91% of the total. The number of OTUs was significantly higher in group L than in group H (P < 0.05). The number of OTUs decreased with the increasing dietary concentration-roughage ratios. 2) The Chao and Ace indexes declined with increasing dietary concentration-roughage ratios. The Ace index was significantly higher in group L than in group H (P < 0.05). The Shannon and Simpson indexes showed no significant differences between the groups. 3) According to cluster analysis, the structure of the rumen microbial community was relatively close in groups L and H. 4) At the phylum level, the relative abundances of Elusimicrobia, Lentisphaerae, TM7, Cyanobacteria, and Spirochaetes were significantly higher in group L than group H (P < 0.05), but the relative abundance of Euryarchaeota had the opposite result. The relative abundances of Proteobacteria and Verrucomicrobia were significantly higher in group L than group M (P < 0.05). 5) At the genus level, the relative abundances of vadinCA11 and Sphaerochaeta were significantly higher in group L than group H (P < 0.05), but the relative abundances of Selenomonas and Methanimicrococcus had the opposite result. 6) At the species level, the relative abundances of Desulfovibrio D168, Ruminococcus albus, Selenomonas ruminantium, and Prevotella ruminicola were significantly higher in group M than group H (P < 0.01 or P < 0.05), but the relative abundances of Ruminococcus flavefaciens and Fibrobacter succinogenes had the opposite result. In conclusion, the diets with different concentration-roughage ratios influenced the microbial community structure of goat rumen, which then affected nutrient digestion and absorption.