PASSIVELY-ACQUIRED ANTIBODIES TO SOMATOTROPIN RELEASE INHIBITING FACTOR (SRIF) INCREASE APPETITE AND GROWTH OF MILK-FED LAMBS

Lambs of ewes immunized during pregnancy against somatotropin release inhibiting factor and of corresponding control ewes were separated fro m their dams st birth before sucking and fed artificially, for 5 weeks , mirk harvested mechanically from the ewes. Seven lambs from immunize d ewes and six from control ewes were fed colostrum on the day of birt h, and thereafter, mirk from immunized ewes. A further six lambs from immunized ewes and seven lambs from control ewes were fed colostrum an d milk from control ewes. Lambs fed colostrum then mirk from immunized ewes, irrespective of whether their dams had been immunized, consumed more milk and attained higher growth rates, particularly during the p eriod from 2 to 5 weeks after birth than Iambs fed colostrum and milk from control ewes. Immunized ewes showed evidence for the capacity to produce more milk at improved efficiency of food utilization than cont rol ewes. It is concluded that passively acquired antibodies to somato tropin release inhibiting factor increased appetite and this, together with increased milk yield of immunized ewes, would support increased growth of lambs from immunized ewes.