Student Competition; Immunology, Health, and Disease

The potential of feeding a blend of 3 strains of Bacillus subtilis (Sporulin; SPR), to control Salmonella (SAL) was evaluated in broilers challenged with a strain of Salmonella Heidelberg (SH) isolated in Brazil . A total of 288 broilers were allocated to 6 treatments of 4 replicates of 12 birds each . Groups were T1) Non-challenged (NC), T2) NC fed 250 g of SPR/ton, T3) NC fed 500 g of SPR/ton, T4) SH-challenged (SHC) birds with SH, T5) SHC fed 250 g of SPR/ton, T6) SHC fed 500 g of SPR /ton . At 3 d of age, birds in groups T4, T5, and T6, were orally challenged with 107 cfu of SH /chick . Liver SAL counts; macrophage, CD4+ and CD8+ cell counts; and histology evaluations at the distal ileum by the ISI method (INPIBR1020150036019) were performed at 7 and 21 d of age on 12 birds per treatment . Data were submitted to ANOVA (ANOVA) and Tukey’s test (P < 0 .05) for the means with a significant difference. Feeding 250 g/ton of SPR improved weight gain and reduced SAL counts in liver at 21 d . Feeding 500 g/ton reduced liver SAL counts at 7 and 21 d, and cecal SAL counts at 21d, significantly suggesting an inhibitory effect of SPR against SH . Feeding 500 g/ton of SPR to challenged birds increased lamina propria and epithelial thickness and proliferation of goblet cell and macrophages in ileal mucosa vs . challenged control birds . In non-challenged birds, SPR 500 g/ton reduced liver macrophages and CD4+ cells vs . non-challenged control birds . In challenged birds, 250 g and 500 g/ton of SPR showed greater macrophage counts in liver parenchyma vs . challenged control group suggesting that control of SH could be associated with increased macrophage presence in liver and an immune modulatory effect of SPR at the highest dose . The treatment with SPR 250 g/ton improved weight gain and reduced the liver SH isolation at 21 d . The treatment with SPR 500 g/ton did not affect the performance but reduced the SH isolation in liver at 7 and 21 d, suggesting an early control of the SH infection .