Abstract
The objective of the present study is to examine the effects of probiotics, organic acids, and their combination on growth performance, carcase characteristics, blood biochemical parameters, antioxidative status, immune responsiveness, and bacterial count in broilers. A total of 1,200 1-d-old unsexed broiler chicks (Ross 308) were randomly assigned in a completely randomised design according to a 2 x 3 factorial arrangement, with 2 levels of dietary probiotics (0% and 0.2%) possessing 4 x 10(9) cfu/g of Bacillus subtilis and Bacillus licheniformis and 3 levels (0, 0.03, and 0.06%) of organic acids blend of acetic and propionic acids for a total of 6 experimental treatments with 10 replicates each (20 birds/replicate). Dietary 0.02% probiotics increased final body weight. Addition of probiotics or organic acids increased plasma total protein concentration significantly. Dietary 0.02% probiotics increased plasma glutathione peroxidase (GSH-Px) concentration and enhanced humoral- and cell-mediated immune response. Supplementation of 0.03% and 0.06% organic acids improved cell-mediated immune response significantly. Interestingly, addition of probiotics and/or organic acids reduced total bacterial count in breast meat, and Salmonella was not detected in meat. A significant interaction between probiotics and organic acids was observed in plasma globulin concentration, plasma GSH-Px concentration, cell-mediated immune response at 24 h post-phytohaemagglutinin-P injection, intestinal Salmonella count, and total bacterial count in meat. It could be concluded that the inclusion of probiotics and/or organic acids enhanced humoral- and cell-mediated immunity and decreased the counts of E. coli and Salmonella in the gut, and reduced total bacterial count in breast meat.