The Effect of a Synbiotic Applied as a Coarse Spray at the Hatchery Versus Early Drinking Water Application on Broiler Chick Performance and Intestinal Morphology

Antibiotic resistance is a threat to human and animal medicine, causing major restrictions on antibiotic use in broiler production. Synbiotics are being investigated as alternatives to antibiotics by supporting overall bird growth and gut health. A study was conducted to examine the effects of a synbiotic on production parameters and early intestinal morphology of broilers using a 2x2 factorial arrangement. The four treatments utilized were: 1. no synbiotic applied, 2. synbiotic applied only as a coarse spray on the day of hatch, 3. synbiotic applied only in the drinking water for the first 3 days, and 4. synbiotic applied as both a coarse spray on day of hatch and in the drinking water for first 3 days. The product was prepared according to the manufacturer’s specifications where each chick received 1x108 CFU/day. The synbiotic contained inulin, Lactobacillus reuteri, Bifidobacterium animalis, Pediococcus acidilactici, and Enterococcus faecium. Sixteen flocks of Ross 708 broilers were raised in commercial broiler houses for 7 weeks. Each treatment was randomly assigned to four flocks/treatment. First week mortality (FWM), overall mortality (OM) and body weights (BW) at 7 and 49 days of age were measured. FWM for treatment 1 was 1.18%, for treatment 2 was 1.34%, for treatment 3 was 1.19%, and for treatment 4 was 1.22%. Jejunum samples were taken on 3 and 10 days of age. Villi height, crypt depth, and villi:crypt ratio were measured. A novel scoring system was used to quantify the extent of epithelial sloughing and damage observed on villi tips. Scores from 1-4, where 1 is least damaged and 4 is most damaged, were assigned. Statistical analyses were performed using the GLIMMIX procedure of SAS. The model used included the fixed effects of spray and water and their interaction. Fisher’s protected LSD was used for all comparisons among the Least Squares Means using an alpha0.10) on FWM, OM, BW, villi height, crypt depth, or villi:crypt ratio. The treatment applied as a coarse spray did not significantly affect jejunum epithelial scores. However, the synbiotic treatments significantly increased epithelial damage observed on villi tips using the novel scoring system (p\u3c0.10) suggesting a more compromised epithelial later and less nutrient digestion and absorption in the jejunum. Although growth and performance did not suffer, the observed reductions in small intestinal epithelial integrity may lead to future production losses like inefficient weight gain, increased disease challenges, and elevated mortality. Advisor: Sheila E. Purdu