Effects of probiotic supplement (Bacillus subtilis and Lactobacillus acidophilus) on feed efficiency, growth performance, and microbial population of weaning rabbits

Objective: This study aimed to investigate the effects of single or/and double strains of probiotic supplement on feed efficiency, growth performance, and microbial population in distal gastro intestinal tract (GIT) of weaning rabbits.Methods: Sixtyfour weaning (28 days old) New Zealand White rabbits were randomly distributed into four groups with treatments including: basal diet without probiotic supple ment (control) or supplemented as follows: 1×10 6 cfu/g B. subtilis (BS group), 1×10 7 cfu/g L. acidophilus (LA group), or 0.5×10 6 cfu/g B. subtilis plus 0.5×10 7 cfu/g L. acidophilus (BL group).During the research, the male and female rabbits were fed separately.Body weight of the rabbits was recorded at 28, 42, and 70 d of age.Results: There was an increase (p<0.05) in body weight gain for the LA group at 42 d.Rabbits fed BL responsed with a greater growth (p<0.05)and better feed conversion ratio (p<0.05)than those fed with no probiotic.Digestibility coefficients of dry matter, organic matter, crude protein, neutral detergent fiber, and gross energy were higher (p<0.05) in LA and BL groups than those in the control group.Male rabbits had higher (p<0.05)Bacilli spp.and Coliformis spp. in the ileum than female rabbits.Rabbits supplemented with BS had greater (p<0.05)numbers of bacilli in all intestinal segments than those receiving no probiotic, whereas intestinal Lactobacilli populations were greater (p<0.001) in the LA and BL diets compared to control.Average intestinal coliform populations were lowest (p<0.05) in the rabbits supplemented with LA as compared to those fed the control and BS.Conclusion: Supplementation of L. acidophilus alone or in combination with B. subtilis at a half of dose could enhance number of gut beneficial bacteria populations, nutrient digestibility, cecal fermentation, feed efficiency, and growth performance, but rabbits receiving only B. subtilis alone were not different from the controls without probiotic.