Thesis (M.Sc.)--Chulalongkorn University, 2011

Sixty-four healthy weaning New Zealand White rabbits (28-29 days of age) were used to investigate the effects of probiotic supplement on feed efficiency, growth performance, fecal score, coefficient of total tract apparent digestibility, nitrogen retention, cecal fermentation, and gut microbial populations of weaning rabbits. The animals were fed four diets for 6-week study. A commercial diet with no probiotic was used as a basal diet (control). Three probiotic diets composed of basal diet mixed with either: 1) B. subtilis (BS) spores at 1x10⁶ cfu/g feed, 2) L. acidophilus (LA) at 1x10⁷ cfu/g feed, or 3) a mixture of B. subtilis at 0.5x106 cfu/g feed and L. acidophilus at 0.5x107 cfu/g feed (BL). The results showed that the weaning rabbits supplemented with LA and BL had greater average daily gain, lower feed conversion ratio, greater coefficient of total tract apparent digestibility, and lower fecal score than the rabbits fed the control diet (P<0.05). The animals fed LA had greater nitrogen retention, cecal volatile fatty acids concentration and intestinal lactobacilli population, and lower intestinal coliform population as compared to the control group (P<0.05). No significant differences were found on almost all parameters in the animals supplemented with BS as compared to the control group. In conclusion, the present results suggest that L. acidophilus has the potential benefits in terms of probiotic effects in weaning rabbits.