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The objective of this study was to investigate how the interaction between feeding probiotic and different dietary protein levels impacts performance, caecal bacterial population, gut permeability and serum uric acid of chickens under subclinical necrotic enteritis (NE) challenge. The study consisted of two 2 × 2 factorial arrangements of treatments and birds were evaluated from 0 to 24 days of age. Initially, birds subjected to NE challenge (yes or no) and probiotic treatment (yes or no) under standard protein feeding regime (21.5 g/kg) were compared; then data from birds fed with two different crude protein levels (standard (21.5 g/kg) or low (19.5 g/kg)) with or without supplementation of probiotic all under NE challenge condition were analysed. Dietary concentration of probiotic was 1 x 106 CFU of Bacillus amyloliquefaciens CECT 5940 per g of feed. All diets were iso-caloric and formulated to contain same amount of digestible essential amino acids. There were no interaction effects and hence only main effects are presented and discussed. Results indicate that weight gain (WG) and feed conversion ratio (FCR) (P < 0.05) were significantly reduced in NE challenged birds. Feeding probiotic increased WG (P < 0.001) and feed intake (FI) (P < 0.01) and decreased FCR (P < 0.05) followed by an increase in caecal Ruminococcus numbers under both non-challenge and challenge conditions but the effect was more pronounced under NE challenge. Furthermore, probiotic supplementation decreased FCR and increased caecal Ruminococcus population in birds fed low protein diets (P < 0.01) Additionally, serum uric acid levels were lower in birds fed low protein diet (P < 0.001). These findings suggest that supplementation of Bacillus amyloliquefacens CECT 5940 can help to improve performance and/or gut microflora in NE challenged birds fed either standard or low protein diets. |
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