[Attenuated vaccine against rota- and coronavirus enteritis in calves].

Kharalambiev, Kh E; Mitov, B; Georgiev, G K; Sizov, I; Simeonov, S

Tested was the effect of the Bulgarian attenuated vaccine of rota- and corona-viruses 'PoKo-81', via treatment of dry and freshly calved cows (injected into the udder) and newborn calves (peritoneal injection). It was found that calves fed three times daily on milk obtained from cows that had had intramammary injections did not develop clinical signs of a disease following experimental infection with rota- and corona-viruses. When the cows on infected farms were treated in the same way the disease in calves, offered immune milk, dropped to 36 per cent as against calves of unvaccinated cows, with which morbidity ran as high as 85 per cent. Calves vaccinated via the peritoneum did not fall ill after infection with rota- and corona-viruses on the 6th day following vaccination. In experiments on 18 infected farms morbidity among control, unvaccinated calves was 76 per cent, and mortality--6.8 per cent. With vaccinated calves on the same farms morbidity dropped to 44 per cent, and mortality--to 2.5 per cent. The duration of diarrhea in the vaccinated calves was radically lowered. Discussed is the possibility to enhance the protective effect of the vaccine.