Effect of Saccharomyces cerevisiae and Lactobacilli supplementation in diets with varying roughage and concentrate ratio on In vitro fermentation, protozoa population and methane production

Effect of probiotics, Saccharomyces cerevisiae and Lactobacilli, alone and in combination was assessed on in vitro fermentation, ciliate protozoa population and methane production of diets containing varying ratios of roughage to concentrate (R:C). The three diets namely D₁ (R:C;40:60), D₂ (R:C; 50:50) and D₃ (R:C; 60:40) were formulated, which were supplemented with no probiotic (control), Saccharomyces cerevisiae (SS, 125×105 cfu/0.5g), Lactobacilli (LAC, 7.5×105 cfu/0.5 g) or combination of both S. cerevisiae and Lactobacilli (SSLAC, 62.5 ×105 cfu of SS and 3.75×105 cfu of LAC/0.5 g diet DM) and the in vitro dry matter digestibility (IVDMD), metabolites and methane production were measured for a 48 h fermentation. Increasing level of concentrate in diet improved (P<0.05) IVDMD, reduced (P<0.05) total gas and methane production. Concentrate level in the diet had linear (P<0.001) increasing effect on total nitrogen (total-N) and ammonia nitrogen (NH₃-N) whereas TCA-pp-N and TVFA of the fermentation medium did not change. Supplementation of SS, LAC or SSLAC did not effected IVDMD, total gas and methane level of the diets, whereas supplementation of SSLAC decreased (P<0.001) total-N and increased (P<0.001) NH₃-N in fermentation medium; however TCA-pp-N and TVFA levels were not changed. Supplementation of SS and SSLAC increased (P<0.001) propionate level in fermentation medium and reduced (P<0.001) acetate levels. The results of the present experiment indicated that supplementation of S. cerevisiae or combination of S. cerevisiae and Lactobacilli improved nitrogen utilization and increased propionate production with reduced acetate levels, thus altering the microbial fermentation pattern of the diet.