Effects of an organic acid mixture and methionine supplements on intestinal morphology, protein and nucleic acids content, microbial population and performance of broiler chickens

A study was carried out to investigate the effects of dietary supplementation of an organic acids mixture and two methionine supplements on intestinal morphology, protein and nucleic acids content, microbial population and performance of broiler chickens. Six hundred unsexed day-old Ross 308 broiler chicks were used in a factorial arrangement (3 × 2) based on a completely randomised design by four replicates with 25 chicks in each. Experimental diets consisted of: 0% organic acid mixture + DL-methionine (Treatment 1), 0% organic acid mixture + Alimet (Treatment 2), 0.5% organic acid mixture + DL-methionine (Treatment 3), 0.5% organic acid mixture + Alimet (Treatment 4), 1% organic acid mixture + DL-methionine (Treatment 5) and 1% organic acid mixture + Alimet (Treatment 6). A significant increase in jejunum mucosal DNA content was found by using 1% of organic acid mixture compared with those by other levels of organic acids at 21 days of age (P < 0.05). Also Treatments 5 and 6 had a higher mucosal DNA content than other treatments (P < 0.05) in a similar period. While at grower stage, the results have shown that protein content, protein/DNA and protein/RNA ratio by 0.5 and 1% of organic acids mixture significantly increased compared with those in the 0% level (P < 0.05). The addition of 1% level of organic acid mixture significantly increased villus height compared with 0 and 0.5% level of organic acid mixture at 21 days of age (P < 0.05). Highest and lowest villus heights were obtained by Treatments 1 and 6 (P < 0.05). Crypt depth increased by 0.5 and 1% of organic acid at 21 and 42 days of age (P < 0.05). Villus surface was significantly increased by 1% of organic acid mixture compared with that by 0% level at 21 days of age. The use of organic acid levels especially 1% resulted in an increase in lactic acid bacteria and decreased Enterobacteriaceae counts in the ileum of broiler chicken (P < 0.05). Better bodyweight and feed conversion ratio were obtained (P < 0.05) by 0.5 and 1% of organic acids mixture, although no response was found in feed intake and mortality in this respect (P > 0.05). The results of this study have shown improved reactions on intestinal morphometrical parameters and microflora atmosphors, by using 1% organic acid mixture. In contrast no differences were found between Alimet and DL-methionine in all tested parameters.