Johne’s disease is characterised by a long incubation period, and the sensitivity of serological
tests against Mycobacterium avium subspecies paratuberculosis (MAP) is low during the
subclinical stage of infection. Due to the relatively high concentration of immunoglobulins
present in colostrum, testing of this sample might improve diagnostic test sensitivity and
detection of infected animals. Blood, colostrum and whey samples were analysed from
26 vaccinated Merino-cross ewes and were tested for antibodies against MAP by indirect
enzyme-linked immunosorbent assay (ELISA). At the recommended dilution for serum
(1:20), the diagnostic sensitivity (DSe) of colostrum and whey were significantly higher
compared to serum, but not significantly differentfrom each other. The significantimprovement
in DSe when using colostrum compared to serum suggests that it might be possible
to detect a greater proportion of infected animals using this sample.