EFFECTS OF CONSTANT AND CYCLING HOT ENVIRONMENTS ON MITOGEN-STIMULATED PROLIFERATION OF PERIPHERAL-BLOOD LYMPHOCYTES FROM SOWS AND LITTERS

1. Lymphocytes from sows maintained in a constant hot environment (32 degrees C) showed reduced proliferative responses to mitogens PHA (P < 0.02) and PWM (P < 0.01) in comparison to sows maintained in a constant cool environment (21 degrees C). In the piglets the hot constant temperature slightly reduced (P < 0.05) proliferative responses of lymphocytes to PHA. 2. No significant effects of a cycling hot environment (27-32 degrees C) were found for any proliferative responses of lymphocytes from sows and litters. 3. In the constant hot environment, serum cortisol concentrations were significantly reduced in the sows (P < 0.0001) while no differences in serum cortisol concentrations were found in the litters.