Feed utilization and rumen fermentation characteristics of Thai-indigenous beef cattle fed ensiled rice straw with Lactobacillus casei TH14, molasses, and cellulase enzymes

The slow and limited ruminal degradation of carbohydrates is the main poor feature of rice straw, which leads to decreased digestibility and feed utilization. This study aimed to examine the combined effects of molasses, cellulase enzymes, and Lactobacillus casei TH14 ensiled rice straw on feed utilization, ruminal fermentation, nitrogen balance, and the energy metabolism of Thai-indigenous beef cattle. Four male Thai-indigenous beef cattle with an initial body weight of 90 ± 5.5 kg were used in a 4 × 4 Latin square design. Rice straw was fermented with 1) molasses 50 g/kg fresh matter (FM, as control), 2) molasses 50 g/kg FM with L. casei TH14, 3) molasses 50 g/kg FM with cellulase enzymes, and 4) a combination of molasses 50 g/kg FM with L. casei TH14 and cellulase enzymes. Ensiled rice straw by molasses with L. casei TH14 treatment and three combined additives were significantly (P < 0.01) higher in crude protein (CP) than those in the control group. The neutral detergent fiber was significantly (P < 0.01) decreased by the ensiled rice straw with L. casei TH14 and cellulase. In addition, ensiled rice straw by molasses with L. casei TH14 and three combinations of additives had significantly (P < 0.05) enhanced dry matter (DM) digestibility compared to the control treatment. Ensiled rice straw did not alter (P > 0.05) fungal zoospores and protozoal population, except for the mean values of the bacterial population, which significantly (P < 0.01) increased when the animals were fed ensiled rice straw by molasses with L. casei TH14. The propionic acid concentration significantly (P < 0.01) increased at 4 h after feeding and achieved average concentration when cattle were fed ensiled rice straw by molasses with L. casei TH14, molasses with cellulase, or three combinations of additives compared with the control treatment. Total nitrogen (N) per N excretion via beef cattle feces offered ensiled rice straw by molasses with cellulase, and the three combinations of additives were significantly lower than those received by a molasses additive (P < 0.05). In conclusion, ensiled rice straw by L. casei TH14 with molasses or L. casei TH14 with molasses and cellulase provides greater results by preventing CP during fermentation, whereas there was increased digestibility of DM, organic matter, rumen bacterial population, and propionic acid.