Effect of Bacillus subtilis supplementation in low energy diets on broiler performance
2016
Harrington, D. | Sims, M. | Kehlet, A.B.
Studies have shown that direct-fed microbials (DFMs) based on spore-forming bacteria supplemented in poultry feed are able to improve broiler performance. In the present study, the interaction of feed supplemented with Bacillus subtilis and different metabolizable energy (ME) levels in feed on Cobb broiler performance were evaluated. Broilers were fed diets containing an average ME of 3,117 (100% ME), 3,054 (98% ME), 2,991 (96% ME), or 2,930 (94% ME) kcal/kg either with or without B. subtilis (8 × 10⁵ cfu/g feed) in a 4 × 2 factorial design. Birds were fed equal amounts of starter and grower feed to approximate for equal amino acid intake and finisher feed ad libitum. Birds fed diets supplemented with B. subtilis were able to achieve higher final BWs and lower FCRs than their respective controls, irrespective of the level of the energy reduction. When birds were fed B. subtilis and diets containing 3,054 kcal/kg ME (98% ME), they were able to achieve equivalent performance to control birds fed non-Bacillus– supplemented rations containing 3,117 kcal/kg (100% ME). Regression analysis indicated B. subtilis had a ME contribution of +62 kcal/kg feed. This improved the performance of birds fed B. subtilis, and a 2% reduced ME (98% ME) diet resulted in a significantly lower feed cost per kilogram weight gain ($0.399/kg weight gain) compared to control birds fed a standard 100% ME diet ($0.417/kg weight gain) and a potential cost saving of $0.018/kg weight gain. In addition, overall mortality was 2.51% lower in B. subtilis–supplemented groups. Consequently, in addition to confirming the performance benefits associated with B. subtilis, it is suggested that supplementation of B. subtilis in feed confers economic savings as well.
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