Effect of different concentrations of Bacillus subtilis on growth performance, carcase quality, gut microflora and immune response of broiler chickens.

1. An experiment was conducted to study the effects of different Bacillus subtilis concentrations on productivity, carcase quality, immune response and the gut microflora of broiler chickens. 2. There were 5 treatment groups: control, with no added Bacillus subtilis supplementation; and 4 treatment groups receiving feed supplemented with different concentrations of B. subtilis. 3. Weight gain was significantly higher and the feed conversion rate was significantly better in all groups receiving feed supplemented with B. subtilis, regardless of its concentration. The groups given B. subtilis supplementation produced relatively bigger breasts, and smaller carcases and thighs, compared with the control group. 4. The appearance of increased diffuse lymphohistiocytic infiltration and solitary lymphoid follicles in the mucosa, and a stronger response to NDV vaccination, indicate increased immunological responses in chickens fed with the B. subtilis supplemented diet. 5. The higher inclusion rate of B. subtilis did not increase Lactobacillus concentrations in the ileum or in the caecum, but decreased the E. coli population significantly.

The effect of pure Fusarium toxins (T-2, F-2, DAS) on the microflora of the gut and on plasma glucocorticoid levels in rat and swine.

The gut microflora and adrenal cortex hormone levels were monitored in HUNGAHYB piglets of 10-12 kg and in Wistar rats of 100-150 g body weight fed with different pure Fusarium toxins. The feeding of either T-2, T-2 + F-2 and DAS toxins at the 5 microgram/g feed level for one week resulted in the substantial increase of aerobic bacteria count of the intestine. Increase of the DAS dose to a twofold level failed to elicit dose-response and no further increases in bacterial counts were observed. Following the uptake of toxin containing feed, the plasma cortisol and corticosterone levels showed a 2-3 fold rise. Intramuscular administration of toxin T-2 also increased the activity of the adrenal cortex and gut microflora counts also increased. It is suggested that the observed changes in the gut microflora may contribute to the appearance of clinical symptoms developing after feeding of toxins as well as to the triggering and maintaining of the stress.