Effects of feed supplementation with 3 different probiotic Bacillus strains and their combination on the performance of broiler chickens challenged with Clostridium perfringens

The application of probiotics in broiler feed, to alleviate performance deficiencies due to mild infections by coccidia and Clostridium perfringens, is of increasing interest for the poultry industry. Therefore, our objective was to evaluate the capacity of 3 Bacillus strains and their combination as probiotics in vitro and in vivo. Thus, protein and carbohydrate degradation and C. perfringens growth inhibition capabilities were assessed by colometry measurement and an agar diffusion bioassay, respectively. A total of 2,250 1-day-old male broiler chicks were assigned to 5 dietary treatments: 1) non-probiotic-supplemented control (control); 2) control 1 DSM 32324 at 0.8 x 10(6) cfu/g of feed; 3) control 1 DSM 32325 at 0.5 x 10(6) cfu/g of feed; 4) control 1 DSM 25840 at 0.3 x 10(6) cfu/g of feed; and 5) control 1 DSM 32324 1 DSM 32325 1 DSM 25840 at 1.6 x 10(6) cfu/g of feed. A pathogenic field strain of C. perfringens was used to induce the necrotic enteritis challenge on day 19, 20, and 21. All birds and remaining feed were weighed on pen basis on day 0, 21, 35, and 42, to calculate BW gain and mortality-adjusted feed conversion. Mortality and mortality due to necrotic enteritis were recorded daily. On day 21, 45 birds per treatment were evaluated for macroscopic intestinal necrotic enteritis lesions. Performance data were statistically analyzed using an ANOVA and subjected to a least significant difference comparison. Necrotic enteritis lesion scores were statistically analyzed using non-parametric Kruskal-Wallis test. Dunn's test was used for treatment comparison. The tested strains showed different abilities of degrading protein and carbohydrates and inhibiting C. perfringens growth in vitro. The birds fed the multi-train combination presented significantly better performance and lower necrotic enteritis lesion score than those in the control group. Dietary supplementation with probiotics resulted in significantly lower necrotic enteritis mortality. The results demonstrate the suitability of the evaluated Bacillus multistrain combination as an effective probiotic in C. perfringens-challenged chickens.