EFFECT OF TRANSPORTATION AND WEANING ON HUMORAL IMMUNE-RESPONSES OF CALVES

Transportation exposes cattle to stress and results in increased morbi dity and mortality. An investigation was made of the effects of transp ort and another important stressor, weaning, on the immune function of calves by determining humoral immune responses to keyhole limpet haem ocyanin (KLH). In a 2 x 2 factorial designed experiment, suckled calve s were either (1) weaned at housing (day 0) and not transported, (2) w eaned at housing and transported, (3) weaned while still at pasture ni ne to 13 days prior to housing and not transported or (4) weaned al pa sture and transported. All calves were immunized with KLH at housing ( day 0) and serum samples were collected subsequently to determine clas s and subclass anti-KLH antibody responses (IgG(1), IgG(2), IgA and Ig M) by direct ELISA. Increased anti-KLH IgG(1) and IgG(2) concentration s were shown in calves that were weaned prior to housing and transport ed on day 10 (P<0.05 and P<0.01 respectively). Transported calves had increased IgG(1) concentrations on day 20 (P<0.05) compared with calve s that were not transported. However, calves weaned at housing and not transported had increased IgA and IgM responses on day 30 compared wi th the other groups of calves (P<0.05). This study shows that transpor tation and weaning affect the humoral immune responses of suckler calv es and that the effects persist for several weeks. However, the effect s of the treatments were not consistent for all antibody classes measu red.