Effects of Dietary Vitamin C, E and Fat on CD4 to CD8 T Cell Ratios in Peripheral Blood of Heat-stressed Broiler Chicks

The effects of dietary vitamins C (VC), E (VE) and sunllower oil (SFO) on immune responses ofheat-stressed male broiler chickens were evaluated. Ali birds were kept under consistent temperatures from 10:00 to 20:00 and from 20:00 to 10:00 throughout the 1-49 day of age period. Antibodies to Newcastle disease virus (NDV) in serum on thelOth day ofpostimmunization at 18, 35 and 48d of age were determined. At 7wk, CD4/CD8 T lymphocyte ratios in peripheral blood were determined. VC, VE, SFO or their interaction had not signilicant effects on immune responses indices and total mortality. However. chicks fed the VE-supplcmentcd diet had a higher antibody titer against NDV at 18 and 48d of age and higher CD4/CD8 lymphocyte ratios. In addition. increasing SPO from 0 to 2.5%, enhanced anti-NDV levels at 18 and 35d of age and increased CD4/CD8 ratios at 49d of age. Moreover, total mortality was decreased with increaseing VC concentration from 0 to 255ppm, VE from 0 to 288ppm and SFO from 0 to 2.5 and 5%. These results suggest that immune responses and especially mortality in hcat-stressed broiler chickens be ameliorated by use of SFO accompanied by dietary VE or VC supplementation.