There was interaction of media pH level with either lactic acid bacteria (LAB) strain or its doses. Modulation of fermentation by adding LAB was more dose-dependent at high pH than low pH. Response of in vitro fermentation to LAB strains varied between high-forage and high-grain diets. Effect of LAB supplementation on rumen fermentation depended on type of strains and the dose. The LAB3 (E. faecium) could be a better candidate for improving feed digestion in the rumen with high-forage diet.