Submitted to: Southern Poultry Science Society Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: February 21, 2000
Publication Date: N/A
Broiler chickens were examined for the effect of vitamin A (Vit A) deficiency on different immune parameters. Day-old male broilers (Ross x Ross) were fed milo-soybean meal diets with 8000 IU vitamin A/Kg feed (CON) or without added Vit A (A-def). At 25 days of age a group of randomly selected birds from each diet was inoculated orally with a mild dose of Eimeria acervulina (EA) oocysts (10-4/bird) and kept on the same diets. Changes in intestinal intraepithelial lymphocytes (IEL) subpopulations were assessed by flow cytometry at 35 days in both infected and non-infected birds. Whether challenged or not, birds on the A-def diet had fewer IEL, expressing the surface markers CD3, CD4, CD8, TCR1 and TCR2 than those of the CON diet. While CD8+ IEL increased in the CON group in response to EA, no change was found in IEL of A-def birds, suggesting that the latter birds were unable to respond properly to coccidial infection. However, serum samples taken 10 days after challenge showed higher antibody level against a recombinant coccidial antigen (3-1 E) in A-def birds than in CON birds, consistent with lower serum interferon-gamma (IFN-gamma) in the A-def group. A higher number of EA oocysts was recovered from A-def birds than from control (9.2 x 10-8 vs. 5.4 x 10-8, respectively). The proliferative response of spleen lymphocytes to concanavalin A was depressed in A-def birds. These data show that Vit A deficiency compromised local immune defenses of challenged birds leading to systemic infection, as reflected in lymphocyte profiles IFN-gamma, and serum lgs in A-def birds.