A comparison of the immune response of 2003 commercial turkeys and a 1966 randombred strain when fed representative 2003 and 1966 turkey diets.

The immunological performance of modern turkeys (one-third each of the Nicholas Turkey, British United Turkeys of America, and Hybrid Turkey strains) hatched in 2003 (2003 strain) was compared with that of a randombred control turkey strain (RBC2) established in calendar year 1966, when fed representative 1966 and 2003 type diets. The 2003 strain had a higher BW and bursa of Fabricius weight relative to total BW compared with the RBC2 strain (P = 0.0001) when measured at 12 and 13 d of age, respectively. Total antibody response against SRBC did not differ between strains, nor were any differences observed in the IgM antibody levels either during a primary or secondary SRBC challenge. However, RBC2 poults had higher IgG levels (P = 0.02) than the 2003 strain at 7 d post secondary SRBC challenge. No significant differences were observed in the phytohemagglutinin phosphate-mediated toe-web lymphoblastic response. However, the 2003-strain turkeys seemed to have a better swelling response (P = 0.06) than the RBC2-strain turkeys when measured at 24 h post phytohemagglutinin phosphate injection. The modern turkeys also had higher mononuclear phagocytic system function, as measured by clearance of carbon particles from the bloodstream 5 min post intravenous injection of colloidal carbon (P = 0.02). These results indicate that selection over the years of turkeys for improved performance traits has had no adverse effects on most of the immune system indicators when examined prior to sexual maturity in the current study.