| Three experiments were conducted to evaluate the effect of organic acid supplementation in broiler diet on growth performance, pH and microbe in gastro-intestinal tract, nutrient availability, to determine the optimal dose of organic acids in the broiler diet, and to further study the mechanism of organic acids for broiler .Exp. 1 studied the optimum amount of organic acid in broiler diet. 360 AVIN chicken at 1 day of age were allotted into 6 treatments in a single factorial arrangement with 6 replicates per treatment and 10 birds per replicate (pen). The basic diet was added with 0%, 0.05%, 0.1%, 0.2%,0.3%,0.4% Lucta complex acidifier .The experiment lasted for 42 days. The two metabolic tests were carried out during period from day 17 to 20 and from day 38 to 40 to determine nutrient availability. One bird was selected from each replicate and killed on day 21 and day 42 to assay pH in gastro-intestinal tract in and the amount of E.coli. and Lactobacillus in jejunum and in ileum.The results showed that acidifier supplementation in the diet at different levels improved feed intake and daily weight gain in a quadratic manner. The supplementation of organic acid improved the availability of DM, protein, organic compound and energy in the broilers at the age of 0-21 days. Comparing with the control test, the supplementation of 0.05%, 0.3% and 0.4% organic acid improved the availability of protein (p<0.01), and Ca and P availability,(P<0.05) in later stage. pH in the ileum, jejunum, duodenum and caecum were decreased with 10.43% lower in caecum pH for the group of 0.2% organic acid compared to the control group. At the same time, the number of E.coli. and Lactobacillus in jejunum and in ileum was increased to some extent with higher increase of Lactobacillus. Based on all the parameters, it was concluded that 0.2% acidifier in the diet was optimal.Exp.2 was to compare the effect of three kinds of organic acids on growth performance of broilers. 240 AVIN chicken at 1 day of age were allotted into 4 treatments in a single factorial arrangement with 6 replicates per treatment and 10 birdsper replicate (pen). The basic diet was added with 0%,l .5% citric acid, 1.5% fumarate and 0.2% Lucta complex acidifier .The experiment lasted for 42 days. The two metabolic tests were carried out during period from day 17 to 20 and from day 38 to 40 to determine nutrient availability. One bird was selected from each replicate and killed on day 21 and day 42 to assay pH in gastro-intestinal tract in and the amount of E.coli. and Lactobacillus in jejunum and in ileum.Result showed that the supplementation of 1.5% citric acid,1.5% fumarate and 0.2% complex acid could improve the availability of DM, protein, organic matter and energy in the broilers at the age of 0-21 day. Meanwhile, the complex acid could increase Ca and P availability(P<0.05) of the broiler at the age of 21-42. ph value of the content in the caecum was increased at d 42. Citric acid and the complex acid could improve the multiplication of E.coli. and Lactobacillus in jejunum and in ileum, and the multiplication of Lactobacillus was predominant. Based on all the parameters, it was concluded that 0.2% complex acidifier was superior to citric acid and fumarate.Exp. 3 compared effect of organic acid with antibiotic. 180 AVIN chicken at 1 day of age were allotted into3 treatments in a single factorial arrangement with 6 replicates per treatment and 10 birds per replicate (pen). The basic diet was added with 0.2% Lucta complex acidifier or 150mg/kg .The experiment lasted for 42 days. The two metabolic tests were carried out during period from day 17 to 20 and from day 38 to 40 to determine nutrient availability. One bird was selected from each replicate and killed on day 21 and day 42 to assay pH in gastro-intestinal tract in and the amount of E. coli. and Lactobacillus in jejunum and in ileum.Results showed that the supplementation of 150 mg/kg flavomycin and 0.2% acidifier could improve the growth performance of broilers. The addition of 150 mg/kg flavomycin increased the feed intake and the daily weight gain by up to 10.74% and 6.63% respectively in the broilers at the 21 d of age(p<0.05); the supplementation of 0.2% Leda acidificent improved the feed intake and the daily weight gain by up to 4.41% and 7.55% respectively, and feed consumption rate was decreased by 3.96%. Supplementation of 150 mg/kg flavomycin and 0.2% acidifier could improve the availabilities of DM, protein, organic matter and energy in the broilers at the age of 0-21 day. Meanwhile, acidifier addition could increase Ca and P availability,(P<0.05) of the broiler at the 21 -42 of age. ph value of the content in the caecum of the broiler at the 42 of age was decreased for flavomycin and acidifier treatments. The amount of E.coli.and Lactobacillus in jejunum decreased up to 8.93%and5.72% respectively for flavomycintreatment. The addition of 0.2% acidifier increased the amount of E.coli. and Lactobacillus in caecum up to 12.10% and 24.29% respectively (p<0.05) with the multiplication of Lactobacillus.being predominant. Based on all the parameters, it was concluded that supplementation of 0.2% complex acidifier could replace 150 mg/kg flavomycin in terms of the effectiveness on performance and microecology.Implication: The supplementation of the organic acid and flavomycin could improve the growth performance of broilers; Feed intake and weight gain were quadratically responded to the supplementary level of complex acidifier. Nutrient availability and micro-ecological environment of broilers were improved to a certain extent. It was concluded that 0.2% complex acidifier was superior to citric acid and fumarate, and could replace 150 mg/kg flavomycin in broiler diet. |
