| dc.description.abstract | Gastrointestinal tract (GIT) of broiler chickens is a continuous structure that has direct contact with external substances. It is responsible for nutrient absorption, but its contact with external organisms, including bacteria, makes it an important site for health and immunity. Bacterial populations can become a concern if abundance reaches pathogenic levels. Once pathogens are detected in GIT, immune system is activated, characterized by inflammatory reactions. Inflammation is necessary to kill pathogens and decrease negative effects of infections. However, uncontrolled inflammation could lead to host tissue damage and decreased performance. Dietary addition of sub-clinical levels of antibiotics in poultry feed has been used to control bacterial populations in GIT. However, consumer concerns have decreased the use of antibiotics in broiler production. Dietary treatments, including vitamins, have been evaluated as an alternative to improve broiler health and immunity. Vitamin D and its metabolites influence immunity in mammals and have displayed immunomodulatory effects in avian species. Vitamin D is commonly fed as vitamin D3 (D3). Dietary addition of 25-hydroxyvitamin D3 (25OHD3), the circulating form of vitamin D, has resulted in increased broiler performance relative to vitamin D3 supplementation only. Furthermore, 25OHD3 inclusion modulates gene expression of immune related molecules in the GIT of broilers and displays anti-inflammatory effects which help control inflammation. A randomized complete block design experiment with diet as main effect was conducted to evaluate the effect of dietary 25OHD3 inclusion on relative protein expression of cytokines (immune related proteins), Interleukin (IL) -17 and IL-10, and tight junction proteins (GIT integrity related proteins), Zona Occludens 1 (ZO-1) and Claudin-1 (CLD-1), in broiler chicken duodenum and ileum from 3 to 21 d post-hatch. All diets were formulated to provide 5,000 IU of vitamin D per kg of feed. Experimental corn-soybean meal based treatments were: 1) common starter diet containing 5,000 IU of D3 per kg of feed (D3) and 2) common starter diet containing 2,240 IU of D3 + 2,760 IU of 25OHD3 per kg of feed (25OHD3) fed from d 0 to 21. Intestinal tissue samples were collected from 12 birds per treatment on d 3, 6, 9, 12, 15, 18, and 21. Feeding 25OHD3 post-hatch decreased ileal IL-10 protein expression in 21 d-old broilers compared with D3 only (P = 0.0190). Broilers fed only D3 post-hatch had greater IL-17 protein expression in ileum at 18 and 21 d-of-age (P = 0.0412) than those fed 25OHD3. Dietary inclusion of 25OHD3 altered abundance of key inflammatory cytokines in ileum of young broilers. | en_US |
