IUMMUNOLOGY AND MOLECULAR BIOLOGY Effects of Cold Stress on Immune Responses and Body Weight of Chicken Lines Divergently Selected for Antibody

ABSTRACT Effects of cold stress (CS) on the immune system of chicken lines divergently selected for high (H line) and low (L line) antibody responses to SRBC next to a randombred control (C) line were studied. Three- to four-week-old growing chicks of the three lines were feed-restricted at 80 % ad libitum and subjected to CS at 10°C continuously for 7, 5, 3, 1, or 0 d prior to immuniza-tion with keyhole limpet hemocyanin (KLH). Specific and natural antibodies were measured in the three chicken lines subjected to or not subjected to various durations of CS prior to immunization. In addition to antibodies we also measured in vitro lymphocyte proliferation as a measure of cell-mediated immunity (CMI), zymosan-induced reactive oxygen intermediates (ROI) production as a measure of phagocytosis, and BW gain as a measure of production trait. In general, significantly higher antibody responses to KLH and natural antigens were found in the H line as compared to the other two lines. Specific antibody re-sponses to KLH were not significantly affected by CS, but an acute transient increase in natural antibody titers to ovalbumin was found in H line birds subjected to 1 d (Key words: adaptation, chicken, cold stress, immune response