Effects of exogenous fibrolytic enzymes supplementation on growth performance and ruminal fermentation in pre-weaning Simmental calves

Early adaptation of newborn calves’ forestomaches to concentrates and roughage is crucial for cost-effectiveness. Therefore, the use of additives that will facilitate early adaptation to feed and positively impact forestomach development is crucial. This study aimed to determine the effects of exogenous fibrolytic enzyme supplementation on growth performance and rumen fermentation in pre-weaning calves. Eighteen Simmental male calves of the same age (4 days) were randomly assigned to 3 groups and supplemented with exogenous fibrolytic enzyme additive, 0 (Control), 2 g.d- 1, or 4 g,d-1 for 84 days treatments included with exogenous fibrolytic enzyme additive, 0 (Control), 2 g.d-1 or 4 g.d-1. The exogenous fibrolytic enzyme supplementation to calves significantly improved feed conversion ratio (P<0.01). Ruminal pH and ammonia nitrogen (NH₃-N concentrations were not affected by exogenous fibrolytic enzyme supplementation on days 42 and 84 of the study (P>0.05). Ruminal concentrations of acetic acid, propionic acid, and butyric acid were not affected by exogenous fibrolytic enzyme supplementation on day 42 of the study (P>0.05). The propionic acid concentration was higher in both exogenous fibrolytic enzyme -supplemented groups than in the Control group on the 84th day of the study (P<0.01). The butyric acid concentration at 2 g.d-1 exogenous fibrolytic enzyme supplemented group was higher than the other groups on the 84th day of the study (P<0.001). The acetic acid to propionic acid ratio was higher in the Control and 2 g.d-1 exogenous fibrolytic enzyme -supplemented groups than in the 4 g.d-1 exogenous fibrolytic enzyme-supplemented group on the 42nd day of the study (P<0.05). The acetic acid to propionic acid ratio was higher in the Control group than in the exogenous fibrolytic enzyme -supplemented groups on day 84 of the study (P<0.01). The results indicated that 2 or 4 g.d-1 exogenous fibrolytic enzyme supplementation had a better feed conversion ratio and ruminal propionic concentration in pre-weaning calves.