effect of antibiotic and its possible alternatives (organic acid, probiotic, prebiotic) on performance, egg characteristics and blood metabolites of commercial laying hens

this experiment was conducted to evaluate and compare antibiotic, organic acid, probiotic and prebiotic effects on performance, egg quality and blood metabolites in commercial laying hens. the experiment was a completely randomized design with 160 laying hens strain hy line (w-36) from 32 to 42 weeks of age with 5 treatments and 4 replicates of 8 hens each. the experimental treatments consisted: 1- basal diet, 2- basal diet + 150 g/ton oxy tetracycline antibiotic, 3- basal diet + 3 kg/ton of organic acid supplementation, 4- basal diet + 50 g/ton probiotic (protexin) and 5- basal diet + 2 kg/ton of mannan oligosaccharide prebiotic. the results showed that the use of antibiotic, organic acid, probiotic and prebiotic have significant effects on performance and egg quality traits. accordingly, the maximum egg weight was obtained in treatments receiving organic acid and prebiotic that was significant compared to control treatment. egg mass and feed conversion ratio in treatment received prebiotic significantly improved. the maximum egg shell weight was obtained in treatment received prebiotic that compared to the control treatment showed a significant increase. between blood factors, glucose concentration in treatment received organic acid compared to control and antibiotic treatments, significantly increased. consequently the use of organic acids and mannan oligosaccharides can have positive effects on performance and egg characteristics of laying hens.