Influence of hydrolyzable versus condensed tannins supplementation in Liaoning cashmere goats: growth performance, nitrogen metabolism, rumen fermentation, and blood metabolites

This study was conducted to investigate the effects of hydrolyzable versus condensed tannins on growth performance, nitrogen (N) metabolism, rumen fermentation, and blood parameters in Liaoning cashmere goats. A control diet and three experimental diets-supplemented with 0.5% chestnut tannin (CT), tannic acid (TA), or quebracho tannin (QT)-were compared. Goats fed the QT diet had higher average daily gain (ADG) and average daily feed intake (ADFI) than those fed the TA diet (p<0.05). Compared to the control, the QT group exhibited lower fecal N, urine N, and total N output (g/d, p<0.05), along with higher N retention (g/d) and N utilization (g/kg N intake) than the CT and TA groups (p<0.05). The QT group had the lowest urine uric acid level, while the CT and TA groups showed lower creatinine levels than the control (p<0.05). Tannin supplementation increased rumen ammonia-N (NH3-N) concentration and reduced protozoa counts (p<0.05). Plasma concentrations of total protein, globulin, superoxide dismutase (SOD), catalase (CAT), and lysozyme were higher in the QT group than in the CT and TA groups (p<0.05). These results suggest that condensed tannin exerts more beneficial effects than hydrolyzable tannin on growth, N balance, and antioxidant function at equivalent dietary inclusion levels.