Persistence of rinderpest maternal antibodies in lambs

Abstract

Rinderpest antibodies in 166 lambs of different ages, born to vaccinated ewes were studied with avidin-biotin enzyme-linked immunosorbent assay. The mean serum background optical density (OD) value in 20 colostrum deprived lambs and 50 unvaccinated adult sheep was 0.12. The OD values of 166 one to six month-old colostrum-fed lambs ranged from 0.08 to 0.64 and the pooled rinderpest positive serum was 1.44. A peak value of 0.64 was obtained in the first week which gradually declined to become negative for the presence of rinderpest maternal antibodies at around six months of age (OD=< 0.24). Primary vaccination of lambs of vaccinated ewes is therefore considered appropriate at six months of age for effective immunisation with least interference of maternally-derived antibodies.