Study of dietary supplementation of Propylthiouracil on immune cell population and immune response against bronchitis disease in Ross 308 boiler breeder roosters

Current investigation was performed to study the effect of Propylthiouracil on immune cell count and antibody production in Ross 308 broiler breeder roosters with a total of 66 birds in complete randomized design during primary and booster vaccination. The birds were randomly allocated in two experimental groups including replication in each. All chickens were reared in the same condition according to the breeder's management guide for entire 18-wk duration (control group) or up to the point of dietary treatment with Propylthiouracil (0.1% w: w) for 6 weeks through 6 to 12 wk of age (Hypothyroidism group). Birds of both experimental groups were vaccinated at age 9 and 15 wk with using of Bronchitis vaccine Nobilis 4/91 (Intervet, Netherland) in drinking water and then were bled at age 12 and 18 wk. Consumption of Propylthiouracil decrease serum thyroxin (tetraiodothyronine), triiodothyronine and production of antibody hypothyroid group versus control group at age of 12 wk (P<0.05) but there were no differences between experiential groups at age 18 wk (P>0.05). Study of total cell count showed induction of hypothyroidism lead to lower total white cell count and percentage of lymphocyte cell in hypothyroid group versus control group after primary vaccination at age of 12 wk (P<0.05) but there were not significant difference between both experimental group following booster vaccination at age 18 wk (P>0.05). It seems supplementation of feed with Propyl-2-thiouracil and consequent hypothyroidism leads to higher immune response while populations of blood cells had decreased.