Abstract:

The experiment was conducted to study the effects of Bacillus subtilis Natto  on the development of digestive tract in pre-weaning and post-weaning calves. Twenty-four Holstein male calves were used in a complete randomized block design, and was assigned to one of three treatments, 8 calves in each group. The calves in the two experimental treatments were fed Na and N1 Bacillus subtilis Natto while no Bacillus subtilis Natto was fed to the calves in the control group. The calves were fed with milk supplemented with the Bacillus subtilis Natto, and starter diet was also fed to the calves until weaning. Four calves in each group were slaughtered randomly at weaning and others were raised until 8 weeks after weaning. All the calves were slaughtered at the end of the trial. The results showed that compared with the control group, the weight of ruminoreticulum in calves fed Na Bacillus subtilis Natto was significantly enhanced (P<0.05); but the ruminoreticulum pH-value in the calves from N1 group was decreased throughout the experiment, while that of abomasums was dramatically decreased during the beginning period of weaning(P<0.05). The length of the duodenum in the calves fed Na Bacillus subtilis Natto was shorter than the control(P<0.05), so was that of the ileum (P<0.05). In addition, Bacillus subtilis Natto decreased the pH value in the duodenum and the pre-jejunum. In this study, we found that Bacillus subtilis Natto helped the digestion of the nutrients and promote the health of the calves.

Key words: Bacillus subtilis Natto; calves; development of digestive tract