Microbiomic and Metabolomic Insights into the Roles of Hydrolysable Versus Condensed Tannins on the Growth...

This study was conducted to compare the effects of hydrolysable versus condensed tannins on growth performance, nutrient digestion, and rumen fermentation in goats. A total of 27 Liaoning cashmere goats with similar initial body weights were randomly distributed into three groups: a basal diet, a basal diet +0.5% tannic acid (hydrolysable tannin, HT), or a basal diet +0.5% quebracho tannin (condensed tannin, CT), respectively. Compared to the control group, HT showed a decreased (p < 0.05) feed intake, while CT showed an increased (p < 0.05) feed intake and body weight gain. Digestibility of dry matter, crude protein, neutral detergent fiber, and acid detergent fiber did not differ (p > 0.05) among groups. The HT group showed lower pH and acetic acid concentration in the rumen (p < 0.05), while the CT group showed a decrease (p < 0.05) in the abundances of Verrucomicrobia and Methanobrevibacter. Supplementation of CT decreased (p < 0.05) the levels of dihydrouracil, xanthosine, alpha-D-mannose, and L-tryptophan, while HT increased (p < 0.05) these metabolites. In conclusion, this study suggested that responses of ruminal microbiota and metabolite profiles to the type of tannins varied, and CT displayed a more positive effect on the growth performance of goats than HT when supplemented at the same level in the diets.