Effects of Bacillus Subtilis-Zinc on Rats with Congenital Zinc Deficiency

This study investigated the effects of dietary supplementation of Bacillus subtilis-zinc on growth rates of the body and organs, nutrient utilization, microbial diversity in caecum, and contents of zinc (Zn) in organs of rats fed a Zn-deficient diet. In trial 1, 72 female pregnant SD rats were allocated to two groups and respectively fed the basal diet containing 13 mg Zn/kg, or the control diet containing 38 mg Zn/kg by supplementing ZnSO₄ from day 10 of pregnancy until the offspring rats 24 days old. In trial 2, 18 offspring rats from the control group were fed the control diet. Ninety offspring from the Zn deficiency group were allocated to 5 groups and were fed the basal diet drenched with ZnSO₄ solution (the total Zn 38 mg/kg), the basal diet only, or the basal diet drenched with Bacillus subtilis-Zn at doses of 2, 17, and 32 mg/kg Zn respectively. Each group had 3 replicates of 6 rats. The experiment lasted for 5 weeks. We found feeding young rats the Zn-deficient diet reduced feed intake, growth rate, unitization efficiencies of nitrogen (N), and Zn content in the organs. Administration of Bacillus subtilis-Zn to rats increased feed intake and the growth rates of the body and liver, kidney and heart, increased N utilization efficiency, and the contents of Zn in heart and brain but not in liver, regulated microbial diversity in the cecal content. The optimal amount of Bacillus subtilis-Zn ranged 15~20 mg Zn/kg, with the corresponding total Zn level at 28~33 mg/kg diet, the effects of which were superior to these by adding ZnSO₄ at 38 mg/kg.