HUSK IN CATTLE: LABORATORY AND FIELD STUDIES ON CALVES VACCINATED WITH IRRADIATED LUNGWORM LARVAE
The successful use of vaccine consisting of x-irradiated Dictyocaulus viviparus larvae, in 134 calves under farm conditions during 1959-61, is described. The vaccine was safe for use in normal calves and in calves suffering a mild virus pneumonia. Adequate larval attenuation was shown by absence of patent inflections and very little affect on respiratory rate. Experimental challenge with 5000 to 10000 iarvae in 10 calves resulted in mild symptoms but a 2-fold increase in respiratory rate. Natural pasture challenge of calves produced similar mild symptoms except after sudden exposure to a very heavy pasture challenge. The evidence presented indicates that the vaccine used is quite safe to use, in that its pathogenicity is negligible. The failure to find lungworm iarvae in repeated fecal samples from calves during the vaccination process indicates that the level of irradiation used effectively attenuates the larvae and prevents them completing their development to the fertile adult stage. There was no direct connection between the titer and the height of the maximum respiratory increase after vaccination. (TCO)
- Research Organization:
- Univ. of Liverpool, Eng.
- NSA Number:
- NSA-17-021423
- OSTI ID:
- 4728168
- Journal Information:
- Vet. Record, Vol. Vol: 74; Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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