Determining the effect of probiotic in high or low nutrient density diets on growth performance, immune system and some blood parameters of broiler chickens

The purpose of this study was to examine the effect of probiotic as growth promoters and different nutrient density on the performance, immune response, and some blood parameters of broiler chickens. A total of 400 one-day-old Ross broilers were assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement (5 replicates with 20 broilers per replicate) and fed 1 of 4 diets: two levels of nutrient density [high nutrient density (ME 2950 kJ/kg and CP 21.5 %/kg for 0-10 d; ME 3050 kJ/kg and CP20.3 %/kg for 11-24 d; ME 3150 kJ/kg and CP18.7 %/kg for 25-42 d) or low nutrient density (ME 2850 kJ/kg and CP 20.7 %/kg for 0-10 d; ME 2950 kJ/kg and CP19.6 %/kg for 11-24 d; ME 3050 kJ/kg and CP18.1 %/kg for 25-42 d)] and also two levels of probiotics 0 or 1.5 %/kg (65× 107 viable spores/g of Bacillus subtilis). Probiotic and nutrient density had no significant effect on performance of broiler chickens. Serum cholesterol and triglyceride concentration was decreased by low nutrient density diet (P<0.05). Dietary probiotic increased the blood lymphocyte percentage. Probiotic and density had significant effect on hetrophils and H/L ratio and decreased lymphocytes count at the end of expriments (P<0.05).