Effect of tannins and cellulase on growth performance, nutrients digestibility, blood profiles, intestinal morphology and carcass characteristics in Hu sheep

Objective: This study was conducted to evaluate the effects of tannins and cellulase on growth performance, nutrient digestibility, blood profiles, intestinal morphology, and carcass characteristics in Hu sheep. Methods: A total of 48 three-month-old meat Hu sheep (25.05 +/- 0.9 kg) were blocked based on body weight, and randomly allotted to 4 treatments with 3 replicates of 4 sheep each. The experiment lasted for 80 d, and dietary treatments were as follows: i) CON, control diet; ii) TAN, CON+0.1% tannins; iii) CEL, CON+0.1% cellulase; iv) TAN+CEL, CON+0.1% tannins and 0.1% cellulase. Results: Compared with CON, CEL, and TAN+CEL had greater (p<0.05) final body weight (FBW) and average daily gain but lower (p<0.05) feed conversion ratio, while FBW of TAN+CEL was lower (p<0.05) than that of CEL. The apparent total tract digestibility (ATTD) of dry matter in TAN, CEL, and TAN+CEL groups were higher (p<0.05) than that in CON. CEL and TAN+CEL groups had greater (p<0.05) ATTD of crude fiber compared with TAN and CON, while TAN group had lower (p<0.05) ATTD of crude protein than other treatments. TAN, CEL, and TAN+CEL groups increased (p<0.05) serum globulin and alkaline phosphatase but decreased (p<0.05) albumin/globulin. Serum total protein was greatest for TAN+CEL, intermediate for TAN and CEL and least for CON (p<0.05). TAN+CEL group increased (p<0.05) dressing percentage compared with CON, while the backfat thickness of CEL was lower (p<0.05) than that of CON. The villus height of jejunum and ileum in CEL and TAN+CEL groups were greater (p<0.05) than that in CON, and the crypt depth and villus height: crypt depth of jejunum were increased (p<0.05) in TAN, CEL, and TAN+CEL groups. Conclusion: The addition of tannins and cellulase together promoted nutrient digestion, liver protein synthesis and intestinal development and thus improved growth performance and carcass characteristics.