The prevalence of antibodies to Mycobacterium johnei in colostrum deprived lambs.

The prevalence of antibodies to Mycobacterium johnei in pre-colostral lambs in a flock of sheep infected with Johne's disease was investigated. Blood from 134 ewes and their 143 lambs were collected immediately after lambing. Double immunodiffusion and counterimmunoelectrophoresis tests were used to detect antibodies to M johnei. Four (3 per cent) of 135 lambs born to 127 ewes with serological evidence of exposure to M johnei had detectable antibodies in their sera. All lambs fed colostrum from serologically positive ewes had serum antibodies.