Effects of dietary supplementation with antibiotic, organic acid, probiotic and prebiotic on the intestinal morphology and Newcastle disease virus titers of broilers in commercial farms

Abstract

This experiment was carried out to survey the antibody levels against Newcastle disease virus (NDV) and the morphology of ileal villi of broilers in commercial farms. Based on antibiotics and feed additives used, farms were classified in 3 groups as follows (1) Group I was supplied with antibiotic, probiotics and prebiotics; (2) Group II were supplemented with antibiotic, probiotics, prebiotics and organic acids; and (3) Group III was supplied with antibiotic and probiotics. In each farm, ten chicks were sacrificed at day 1, and five chicks were sacrificed at 7, 14, and 28 days old. A total number of 225 Ross 308 broilers at 1, 7, 14 and 28 days of age were selected randomly from nine farms for the titration of antibody against NDV by using Hemagglutination inhibition assay (HI). Furthermore, total 54 ileum samples of chickens on 14 and 28 days old were also collected for measurement of intestinal morphology. The present study showed there were significant differences about the body weights of broilers across farms within the same antibiotics, feed additives and vaccination programs or among different groups at 7, 14 and 28 days of age. However, at the age of 28 days, except Farm 1, 9 (Group I); 4 (Group II) and 3 (Group III), the remaining farms did not meet the criterion of chicken’s body weight. After ND vaccination for broilers at one day old, the mean value of HI antibody titers gradually declined in the first two weeks. Except for Farm 7 and 8, at 14 days old, the remaining farms showed the low antibody titers under 3log2. No significant differences about the antibody titers against ND virus were found in broilers at 28 days of age (P > 0.05) among farms. The findings suggested that the supplementation of antibiotics, probiotics and/or prebiotics and/or organic acids did not have any consistent effects on immune response to NDV and body weights of broilers. However, the morphometric parameters of ileal villi were improved and the positive correlations between body weight and villi height or villi area in ileum segment were found in these chickens.