Research On Animal Production

  This experiment was designed to determine the role of vitamin E and coenzyme Q₁₀ antioxidant on immunity of broilers in cold stress conditions. For this purpose, 500 male chicks in a completely randomized design with 5 treatments, 5 replicates and 20 chicks in each replicate were tested in 25 experimental units. Treatments were: positive control (normal conditions growth without antioxidants), negative control (cold stress without antioxidants), vitamin E (150 mg/kg diet), Q₁₀ (40 mg/kg diet) and E+Q₁₀ (cold stress associated with antioxidants). Temperature was fixed at 15^oC from day 15 until the end pf experimnt. Results showed that the relative weight of spleen decreased in cold stress condition and using of antioxidants improve its relative weight. The relative weight of bursa was increased in cold stress condition (p<0.01). There was no significant difference between treatments in white blood cell parameters, vaccines titer and injecting SRBC showed no significant differences between experimental groups (p>0.05). Results showed that coetaneous basophile Hypersensitivity response to phytohemaglutinin (p<0.01) and proliferation in vitro T cell-mediated immunity (p<0.05) were significant and the use of antioxidants under cold conditions improves cell-mediated immune response. The use of antioxidants especially Q₁₀ under cold stress conditions decreased mortality. The use of antioxidants in cold stress condition improves cell-mediate immune system and decrease mortality.