Acidity of gastrointestinal tract and tibia characteristics of laying hens fed diets supplemented with antibiotic, organic acid, probiotic and prebiotic

This study was conducted to investigate the effect of antibiotic, organic acid, probiotic and prebiotic on acidity of the gastrointestinal tract, blood plasma minerals concentrations and tibia characteristics of laying hens. The experiment was carried out as a completely randomized design with 160 laying hens of hy-line strain (w-36) from 32 to 42 weeks of age with 5 treatments, 4 replicates and 8 hens in each replicate. The experimental dietary treatments consisted: 1-basal diet, 2-basal diet 150 g/ton of diet antibiotic (oxy tetracycline), 3-basal diet 3 kg/ton of diet organic acid supplementation, 4- basal diet 50 g/ton of diet probiotic protoxin, and 5- basal diet 2 kg/ton of diet prebiotic mannan oligosaccharide. Dietary organic acid supplementation significantly decreased the acidity of crop, duodenum and jejunum (P0.05). Tibia ash and external diameter of it significantly increased by organic acid (P