Passively-acquired antibodies to somatotropin release inhibiting factor (SRIF) increase appetite and growth of milk-fed lambs

Abstract

Lambs of ewes immunized during pregnancy against somatotropin release inhibiting factor and of corresponding control ewes were separated from their dams at birth before sucking and fed artificially, for 5 weeks, milk harvested mechanically from the ewes. Seven lambs from immunized ewes and six from control ewes were fed colostrum on the day of birth, and thereafter, milli from immunized ewes. A further six lambs from immunized ewes and seven lambs from control ewes were fed colostrum and milk from control ewes. Lambs fed colostrum then milk from immunized ewes, irrespective of whether their dams had been immunized, consumed more milk and attained higher growth rates, particularly during the period from 2 to 5 weeks after birth than lambs fed colostrum and milk from control ewes. Immunized ewes showed evidence for the capacity to produce more milk at improved efficiency of foodutilization than control ewes. It is concluded that passively acquired antibodies to somatotropin release inhibiting factor increased appetite and this, together with increased milk yield of immunized ewes, would support increased growth of lambs from immunized ewes.