Effects of In Ovo Probiotic Injection and Dietary Supplementation on Growth Performance, Antioxidant Status, and Selected Culturable Intestinal Microorganisms in Broilers.

The present study investigated the effects of in ovo (IO) probiotic injection and dietary probiotic supplementation on growth performance, antioxidant status, and selected culturable intestinal microorganisms in broilers. A total of 540 fertile Ross 308 eggs were allocated to a 2 × 3 factorial arrangement consisting of two in ovo treatments (no injection or probiotic injection) and three dietary probiotic supplementation levels (0, 5, or 10 mL/kg feed). After hatching, 504 chicks were assigned to six treatment groups with four replicate pens per treatment. The control group received no IO injection and was fed a commercial diet. Birds in the Control+P5 and Control+P10 groups received no IO injection and were fed diets supplemented with 5 and 10 ml/kg probiotic, respectively. The remaining treatment groups received IO injection and were subsequently fed diets containing 0, 5, and 10 ml/kg probiotic supplementation. The in ovo application was performed on day 18 of incubation at a dose of 50 µl/egg. No significant interaction between in ovo treatment and dietary probiotic supplementation was observed for growth performance variables. In ovo probiotic application did not affect body weight, feed intake, or feed conversion ratio throughout the experimental period. However, dietary probiotic supplementation negatively affected body weight from the second week onward and adversely affected feed intake during days 8-14, 15-21, and 22-28. Although in ovo probiotic application increased total antioxidant capacity in liver tissue, it reduced the concentrations of vitamin E, retinol, and carotenoids at Day 42. IO probiotic injection increased Bacillus subtilis counts, whereas it decreased Lactobacillus spp. and Saccharomyces cerevisiae counts in intestinal contents. Only high level dietary probiotic supplementation increased Bacillus subtilis counts while decreased Lactobacillus spp counts. In conclusion, in ovo probiotic administration primarily affected hepatic antioxidant status and selected culturable intestinal microorganisms, whereas continuous dietary supplementation at the tested doses adversely affected growth performance.