Abstract
The aim of this study was to evaluate the impact of a probiotic Bacillus licheniformis strain (DSM 28710; B-Act®) on growth performance and its capacity to mitigate necrotic enteritis (NE; induced via a Clostridium perfringens challenge) in poultry. A broiler trial was conducted, examining three treatments for 42 days under an induced NE challenge; a negative control (basal diet only); an antibiotic treated group (oxytetracycline hydrochloride (OXT), therapeutic dose of 105 mg OXT/litre in drinking water, for three days after C. perfringens challenge); and a B-Act group (500 g B-Act/tonne of feed, equalling 1.6×1012 colony forming units B. licheniformis DSM 28710/tonne of feed, supplemented from start until finish). Despite the induced NE challenge, weight gains of the B-Act and OXT groups were similar to each other but significantly higher compared to the control at the end of the study (P<0.05). Weight gain of the B-Act group was already significantly higher compared to the control on day 21 (P<0.05), indicating a potential benefit of the probiotic even before clinical establishment of NE. Feed conversion ratio (FCR) values followed a similar pattern throughout the study, with a significantly lower overall FCR for the B-Act and OXT groups compared to the control (P<0.05; d0-42). Birds fed B-Act had significantly (P<0.05) lower NE lesions compared to the control and OXT group on day 21, although OXT was not supplemented to the animals at this stage yet. Both B-Act and OXT groups had significantly (P<0.05) lower NE scores than the control on day 28, demonstrating the effectiveness of the antibiotic treatment and the mitigating effect of B-Act on the effects of a Clostridium perfringens induced NE challenge.
Highlights
Both clinical and sub-clinical gastro-intestinal diseases in broilers can lead to major losses, poor welfare and reduced profitability on farm
Challenging the birds with C. perfringens in the phase (d19-21) influenced Feed intake (FI) heavily, with significantly lower values in the control group compared to the B-Act and OXT groups (d0-35; P
The results presented here are in line with previous B. licheniformis studies: Knap et al (2010) conducted three trials, finding that feeding B. licheniformis to broilers challenged with C. perfringens could mitigate the challenge’s negative effects on performance, Necrotic enteritis (NE) mortality and NE lesion scores
Summary
Both clinical and sub-clinical gastro-intestinal diseases in broilers can lead to major losses, poor welfare and reduced profitability on farm. C. perfringens is a Gram-positive, spore-forming, anaerobe bacterium and is normally found at levels of less than 105 colony forming units (cfu)/g intestinal content in healthy birds (Caly et al, 2015). As such, it can be classified as an opportunistic pathogen, only causing NE if the conditions for bacterial overgrowth are optimal (Williams, 2005). Seasonal and environmental influences have an impact on NE occurrence, as well as predisposing factors such as – but not limited to – nutrition (including protein sources and physical feed forms), the presence of coccidiosis, stress and potential immunosuppression (M’Sadeq et al, 2015)
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