Vaccination of kids under one month of age with a killed vaccine and reduction in the frequency of faecal shedding of Mycobacterium avium subspecies paratuberculosis

•Goats vaccinated against paratuberculosis before one month of age.•The average annual milk production levels of vaccinates was significantly higher.•Vaccination was associated with a reduction in the frequency of faecal shedding.•Vaccination stimulated both the cell-mediated and humoral immune systems.•A killed vaccine was efficient in these conditions.

A study was conducted under field conditions in two French dairy goat herds in order to evaluate the efficacy of a killed MAP vaccine in goats vaccinated before one month of age, by measuring production, epidemiological and pathogenetic effects. In each herd, half of the replacement kids were vaccinated, the other half were used as controls. Samples of blood/sera and faeces were collected from each goat at intervals of approximately every seven months for 31 months, to evaluate immune responses and faecal shedding. Goats culled during the study were submitted to 'post-mortem' examinations (gross lesions, culture on tissues and ZN staining). The milk production of each goat was recorded for the first four years of lactation. Compared to controls, the average annual milk production levels of vaccinates was significantly higher. Vaccination was associated with a reduction in the frequency of faecal shedding. The percentages of shedding goats detected by faecal culture dropped significantly to 0% versus 4% at 15.5 months PV, 3% versus 16% at 23 months PV and 8% versus 20% at 30.5 months PV, in vaccinates and in controls, respectively. The stimulation of both the cell-mediated and humoral immune systems by vaccination was evident from the elevated proportion of positive reactors for both tests in vaccinates compared to controls. To conclude, this study confirmed the results previously obtained in goats on the efficacy of a killed vaccine in controlling paratuberculosis by reducing faecal shedding of MAP.