PSIX-2 Potential role of rumen microbiota in altering average daily gain and feed efficiency in meat goats fed simple and mixed pastures using bacterial tag-encoded FLX amplicon pyrosequencing

Abstract

Abstract Our objective was to examine whether the comparative abundance of the Bacteroidetes (B) and Firmicutes (F) bacterial phyla in meat goats fed simple and mixed forages influenced average daily gain (ADG), rumen fermentation parameters and bacterial diversity changes using a tag-encoded FLX amplicon pyrosequencing (bTEFAP). Thirty-six Kiko-cross growing meat goats (BW = 27.7 ± 2.83) at approximate age of 7 mo were used in this study. Animals were randomly allocated to three pasture treatment groups (n = 12) as follows: (1) bermudagrass (BG; Cynodon dactylon), (2) sun hemp (SH; Crotalaria juncea) forage, and (3) BG + SH forage combinations for 45-d. Results indicated that there were no differences in initial BW among treatments, but final BW and ADG were higher (P < 0.01) for SH and BG + SH combinations than for BG alone. We investigated the alterations between the different forage diets and found that ADG and rumen fermentation (A/P ratio), were highly correlated with the abundance of various bacterial populations within the rumen microbiome. There were linear decreases in percentage of Bacteroidetes (R2 = -0.84; P < 0.05) associated with decreasing ADG. In contrast, increased ADG was linearly associated with higher percentages of Firmicutes (R2 = 0.79; P < 0.05), F/B ratio (R2 = 0.88; P = 0.07), total VFA (R2 = 0.45; P < 0.05), and lower A/P ratio (R2 = -0.72; P < 0.01). This suggest that the substrate and bacterial community have the role in adapting host biological parameters in meat goats. The abundance examination of both Bacteroidetes and Firmicutes will be useful for exploring the structure of gut microbiota as an estimate of animal performance.