The effect of antibody to caseous lymphadenitis in ewes on the efficacy of vaccination in lambs
1991
Paton, M.W. (Western Australian Dept. of Agriculture, Northam. Epidemiology Branch) | Mercy, A.R. (Western Australian Dept. of Agriculture, Perth. Epidemiology Branch) | Sutherland, S.S. | Ellis, T.M. (Western Australian Dept. of Agriculture, Perth. Animal Health Lab.) | Duda, S.R. (Chapman Road Veterinary Clinic, Geraldton (Australia))
Lambs were allocated to treatments according to the vaccination history or level of CLA toxin antibody of their dam; they were vaccinated twice using 2 different inoculation regimes; then artificially infected with CLA organisms; the number of lambs with CLA lesions was noted at slaughter. In one experiment high levels of antibody in dams reduced the efficacy of vaccination at 2 and 8 or 8 and 14 weeks of age; in another, the efficacy of vaccination was affected at 8 and 12, but not at 14 and 18 weeks. Infection rates of lambs from dams vaccinated or not were not significantly different, but vaccination of lambs at 2 and 8 weeks was less effective than vaccination at 8 and 14 weeks, probably because younger lambs were less immunocompetent.
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