حذف آنتی بیوتیک محرک رشد (لینکومایسین) و افزودن اسید استیک به جیره جوجه های گوشتی محمد روستایی علی مهر*1،حدیث مویدی احمدسرایی2 و محمود حقیقیان رودسری1

Background:use of acetic acid, as a feed additive, improved broiler chickens performance via modifying intestinal microflora.objectives:experiment was conducted to test the possibility of replacing antibiotic growth promoters with acetic acid.methods: this study was performed by using 144 broiler day-old chicks. birds were split into four groups and each group divided into three subgroups (replicates) which contained 12 chicks at 6 days. the amount of 3 mg/kg lincomycin hydrochloride (an), zero (aa0), 0.7 (aa0.7) and 1.4% (aa1.4) acetic acid were added to diet of each group. at 18, 28 and 38 day, one bird of each subgroup was slaughtered and its ileosecal contents were picked. cfu/g of coliforms, e. coli and lactobacillus of samples were determined. results:the lowest of feed intake (104.91 and 104.90, respectively), the highest of daily gain weight (60.97 and 61.01, respectively) and the lowest of feed conversion ratio (1.72 and 1.72, respectively) were achieved by aa0.7 and aa1.4 at the entire period (p < 0.05). cfu/g of e.coli was lower in aa1.4 (5.26 and 5.40) than aa0 (6.32 and 6.45) and an (5.73 and 5.60; p < 0.05) at 28 and 38 day. cfu/g of lactobacillus was lower in aa0 (6.06) than aa0.7 (6.71) and aa1.4 (6.70) at 28 day (p < 0.05) and there was no difference between aa0 and an (6.49; p > 0.05). cfu/g of lactobacillus was lowest in aa0 (6.14; p < 0.05) and there was no difference among other treatments at 38 day (p > 0.05). conclusions: due to improved food intake, daily gain weight, feed conserve ratio, cfu/g of intestinal harmful and helpful bacteria, replacement of lincomycin with acetic acid in the diet of broiler chickens is possible