effects of dietary antibiotic, probiotic, prebiotic and organic acid as growth promoters on growth performances and ileal digestibility of nutrients in commercial ross broilers

this experiment was conducted in order to determine the effects of different dietary growth promoters on growth performance and nutrient digestibility in male broiler chickens. a total of 360 male broiler chicks (day-old ross 308 strain) were distributed into a completely randomized design (crd) having 6 dietary treatments with four replicates and 15 birds in each replicate. experimental treatments were: 1) basal diet, 2) basal diet + 15 ppm virginamycin antibiotic, 3) basal diet + 0.1 g/kg protexin probiotic) aspergillus oryzae, lactobacillus acidophilus, l. rhamnosus, l. plantarum, l. bulgaricus, bifidobacterium bifidum, enterococcus faecium , streptococcus thermophilus and andida pintolopesii), 4) basal diet + 0.1 g/kg immnowall prebiotic (mannanoligosaccharide), 5) basal diet + 0.45 g/kg digestarom medicinal plant extract, and 6) basal diet + 0.4 g/kg formycin organic acid. ileal digestibility of nutrients was determined using titanium oxide marker at 21 and 42 days of age. results of this study indicated that chicks fed diets supplemented with growth promoters had greater average daily gain and lower feed conversion ratio compared to those fed the control (basal) diet (p<0.05). furthermore, using growth promoters in the diets led to more energy availability and greater ileal protein digestibility (p<0.05). however, ileal ether extract digestibility was not significantly influenced by the experimental treatments (p>0.05). there were no significant differences between relative weights of thigh, breast, and liver due to dietary treatments (p>0.05). relative weights of spleen and bursa of fibricius were significantly higher in birds fed diets supplemented with growth promoters than in those fed the control diet (p<0.05). abdominal fat was found to be significantly higher in antibiotic-supplemented group than in the control group (p<0.05).