Physiologic and immune responses associated with 48-hour fast of pigs

We sought to determine the effect of 48 hours of fasting on physiologic and immune responses of pigs. Sixteen crossbred barrows, approximately 8 weeks of age, were housed in a controlled environment (21 degrees C, 45% RH) with feed and water ad libitum. After 10 days, eight pigs were fasted for 48 hours with water available ad libitum; the remaining eight received feed and water ad libitum. Blood samples were obtained by venipuncture before fasting, at the end of 48-hour fasting, and 3 and 10 days later. No significant differences in responses to mitogens PHA or Con A were noted in whole blood or isolated lymphocyte cultures. Changes in numbers of leukocytes, neutrophils, and serum cortisol concentrations, but not of lymphocytes, were significant. The results suggested that short-term fasting transiently reduces the number of neutrophils and increases serum cortisol concentrations, with no effect on blastogenic responses of lymphocytes to selected mitogens.