Effects of Lactobacillus acidophilus supplementation for improving in vitro rumen fermentation characteristics of cereal straws

Abstract

We explored and compared the effects of four doses (0, 0.25 × 107, 0.50 × 107, and 0.75 × 107 cfu/mL) of Lactobacillus acidophilus supplementation on ruminal fermentation characteristics of maize stover and rice straw. The maximum gas production (Vf) for maize stover and the rate of gas production during early incubation (FRD0) for rice straw were quadratic (p < .05) and linear (p < .01), respectively, and increased when supplemented with L. acidophilus. The L. acidophilus supplementation increased ruminal NH3-N concentration for maize stover (p < .01) and rice straw (p < .05), respectively. The supplementation level of L. acidophilus did not affect the production of volatile fatty acids (VFAs) except for valeric acid, nor did it affect CH4 production, IVDMD, IVNDFD, ruminal pH value, total volatile fatty acids (TVFAs) or the ratio of acetic to propionic acid (A:P). As a fermentation substrate, when compared to rice straw, maize stover increased in vitro gas production parameters (e.g. Vf, k, FRD0 and t0.5), IVDMD, IVNDFD, ruminal NH3-N concentration and TVFAs, whereas there was no (p > .05) difference in CH4 production, ruminal pH value or A:P between the two substrates. The results indicate that L. acidophilus increase in vitro gas production and ruminal NH3-N concentration when using either fermentation substrate, with the greatest increase observed at a dosage of 0.75 × 107 cfu/mL. Additionally, maize stover is superior to rice straw as a fermentation substrate or forage for ruminants. The present positive in vitro results should be tested using in vivo experiments in future.