The Effects of Various Feed Forms and Dietary Supplements (Probiotic and Antibiotic) on Performance, Immune System, Cecal Microbiota, and Intestinal Morphology in Broiler Chickens

This study was conducted to evaluate the effects of feed form (FF) and dietary supplements on performance, immune system, cecal microflora, and intestinal morphology in broiler chickens. A total of 960 one-day-old Ross 308 mixed-sex chickens were distributed to 8 treatments consisting of 6 replicates (20 birds/pen). The experimental design was a 2×4 factorial arrangement of treatments evaluating two feed forms (mash or pellet) and dietary supplements [without a supplement, Lactobacillus acidophilus (L. acidophilus), Bacillus subtilus (B. subtilus), and Avilamycin (an antibiotic)]. Considering the main effects, dietary supplements and pellet diets significantly improved growth performance parameters (FI, BWG, and FCR) compared to the other treatments. Birds fed with a pellet diet had a reduced relative weight of the gizzard and pancreas, increased villus height, and gained the relative weight of the liver and small intestinal. Regardless of the FF, B. subtilis supplementation tended to greater villus height, lower crypt depth, and higher villus height to crypt depth ratio compared to other groups. Birds fed with mash diets supplemented with L. acidophilus and B. subtilis and a pelleted diet supplemented B. subtilis had higher villus height, goblet cell, and Lactobacillus population in the gut compared to the other treatments. Probiotics supplementation reduced the percentage of heterophils compared to other diets. The significant interaction between FF and dietary supplements showed that L. acidophilus in the mash diet tended to enhance the percentage of lymphocytes and reduce the heterophil to lymphocyte ratio compared to the pelleted diet. The main factors had no significant effect on anti-SRBC antibody titer. The results from this study indicated that the probiotic L. acidophilus and B. subtilis used in the mash diet may serve as alternatives to an antibiotic.