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Effects of Spirulina (Arthrospira) platensis and Bacillus subtilis PB6 on growth performance, intestinal microbiota and morphology, and serum parameters in broiler chickens

Context The use of microalgae as prebiotics in poultry diets may improve production efficiency by modifying the gastrointestinal ecosystem. Prebiotic properties of the cyanobacterium Spirulina (Arthrospira) platensis have been confirmed, but effects of its combination with probiotics on broiler chicken performance are unclear. Aims This experiment was designed to study the effects of different levels of a microalga (Spirulina platensis) and a probiotic (Bacillus subtilis PB6, BSPB) on performance, intestinal microbiota and morphology, and blood parameters in broiler chickens. Methods One-day-old Ross 308 broiler chickens (300 in total) were allocated to six treatments in a completely randomised design with 3 × 2 factorial arrangement including three levels of Spirulina (0%, 0.05% or 0.1% of diet) and two levels of BSPB (0% or 0.05% of diet) and were reared for 42 days. Key results Individual use of Spirulina and BSPB improved bodyweight gain and feed conversion ratio of broiler chickens. The relative weight of the breast cut was greater in broilers treated with 0.05% Spirulina than in those receiving Spirulina-free treatments. The count of lactic acid bacteria was higher in the ileum of birds receiving only BSPB than in those receiving diets without BSPB. The use of 0.1% Spirulina in the diet decreased the pH and coliform population in the ileum compared with 0% Spirulina. There was an interaction between Spirulina and BSPB on villus height (VH) and the VH : crypt depth ratio in the small intestine. Co-supplementation with 0.1% Spirulina and BSPB increased VH and the VH : crypt depth ratio in the duodenum compared with diets supplemented, respectively, with 0.1% Spirulina and BSPB alone. Broiler chickens fed diets with BSPB had higher activities of superoxide dismutase and glutathione peroxidase and lower concentrations of cholesterol and triglyceride in serum. Conclusions The results show that supplementation with Spirulina and BSPB had a positive effect on performance and carcass quality of broiler chickens. The synergistic interaction between these supplements leads to enhancement of epithelial morphology in the small intestine. Implications Because of the potential of Spirulina and BSPB to create beneficial changes in the intestinal ecosystem and serum parameters, these dietary additives could be recommended for improving the quantity and quality of meat products and health status in broiler chickens.