Adding dried distillers grains with solubles influences the rumen microbiome of meat goats fed lespedeza or alfalfa-based diets

We evaluated the effect of replacement of corn and soybean meal (SBM) with dried distillers grains with solubles (DDGS) in sericea lespedeza (SL; Lespedeza cuneata) and alfalfa (Medicago sativa)-based diets on ruminal fermentation and bacterial community of growing meat goats. Thirty-six male Spanish growing meat goats with an average body weight of 24 ± 1.8 kg were stratified by body weight and assigned to four isonitrogenous (crude protein = 17.1 ± 0.1%) and isocaloric (3.2 ± 0.09 Mcal/ kg DM) diets for 60 d in a randomized design with a 2 × 2 factorial arrangement. The dietary treatments were (1) alfalfa-based diet (ALC), (2) alfalfa + DDGS (ALD; replacement of corn and SBM with DDGS), (3) SL-based diet (SLC) and (4) SL + DDGS (SLD; replacement of corn and SBM with DDGS). The goats were slaughtered, and rumen contents were immediately sampled for 16 S rRNA gene sequencing and rumen fermentation analysis. The analysis of Similarity (ANOSIM) and linear discriminant analysis (LDA) effect size (LEfSe) were respectively used to detect microbial community shift and differentially abundant taxa among treatments. Addition of DDGS increased (P < 0.05) rumen acetate concentrations in both alfalfa and lespedeza-based diets. However, dietary DDGS reduced (P < 0.05) butyrate and ammonia nitrogen concentrations, compared to alfalfa and SL-based diets. The ANOSIM results revealed a shift in the bacterial community between ALC and ALD (R = 0.251; P = 0.01) and between SLC and SLD (R = 0.289; P = 0.001). The LEfSe analysis revealed that the relative abundance of 7 taxa, including Ruminococcaceae UCG 002, Succinivibrionaceae UCG 002, Prevotellaceae YAB2003, and Lachnospiraceae UCG 010 were reduced (LDA > 2; P < 0.05) while 38 taxa were enriched (LDA > 2; P < 0.05) in ALD compared to ALC. Similarly, the relative abundance of 31 taxa, including Ruminococcus YE281, Succinivibrio, and Lachnospiraceae ND3007 were reduced, while 35 taxa were enriched (LDA > 2; P < 0.05) in SLD compared to SLC. In conclusion, this study showed that regardless of the forage type, inclusion of DDGS in diet modulates the relative population of both fibrolytic and butyrate-producing bacteria in meat goats.