Acute thermal stressors and synthesis of antibodies in chickens.

Three experiments utilizing 368 chickens were conducted to determine the effect of acute heat and cold stress on antibody (Ab) production to sheep red blood cells (SRBC). All birds were injected with 1 ml of a 7% suspension of SRBC within 24 hr of initiation of the thermal stress. Each experiment used the same heat and cold stress regimen: four 30-min exposures to thermal treatments during four consecutive hours. In the first experiment, 40 five-week-old Hubbard broilers were either heat-stressed at an air temperature of 42 C or held at an ambient temperature of 24 C. While no differences (P greater than .10) were observed, antibody titers (log2: mean +/- SE) on day 5 after antigen injection were 10.12 +/- .24 and 9.41 +/- .24 for the control and heat-stressed birds, respectively. In the second experiment, 41 nine-week-old Hubbard broilers were held at air temperatures of 42 C or 26 C. No differences (P greater than .10) were observed in either total titers, 2-mercaptoethanol (ME) sensitive, or ME-resistant Ab titers. In Experiment 3, 72 chicks from each of the Athens Randombred, New Hampshire and White Leghorn breeds, and Hubbard broilers were acutely heat-stressed (41 C), cold-stressed (6 C), or maintained at 24 C. There were no differences (P greater than .10) in Ab titers among treatment groups. In contrast to previous reports, these data indicate that an acute, intermittent heat, or cold stress does not significantly alter the ability of several commercially available breeds of chickens to synthesize antibodies to sheep red blood cells. The effect of chronic themal stressors on the immune system of poultry remains unknown.