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A vaccination study was conducted for infectious bovine keratoconjunctivitis (IBK) in 440 purebred Hereford cattle (cows and their newborn calves) of the USDA Meat Animal Research Center cattle herd at Clay Center, Ne. The cattle were allotted to 4 groups: 60 calves were vaccinated with an autogenous Moraxella bovis bacterin (group 1); 60 calves that were matched with group 1 calves were designated nonvaccinated matched controls (group 2); 99 calves were peer group nonvaccinated controls (group 3); and 219 cows, the dams of the calves, were nonvaccinated consorts (group 4). The infection rates in cattle groups 1, 2, 3, and 4 during the summer were 96.6, 98.3, 100, and 79.1%, respectively, and the disease rates were 90, 93, 85, and 20%. The infection and the disease rates were significantly (P less than 0.01) different between claves and cows. The disease rate was also significantly different between older and younger cows. A larger percentage of the affected calves and cows had mild or moderate (61%) signs of IBK rather than severe (39%) signs. The rate of body weight gain was reduced in calves with severe signs of IBK. The results seemed to indicate that little would be gained by vaccinating cattle against IBK under the conditions of study.

A vaccination study for infectious bovine keratoconjunctivitis was conducted on 108 newborn Hereford calves in the US Department of Agriculture Meat Animal Research Center cattle herd at Clay Center, Nebraska. Groups were allocated so that age of calf, sex of calf, and age of dam were equally distributed between the 54 vaccinated (group I) and the 54 nonvaccinated (group 2) control calves. The dams of both groups of calves were monitored as group 3 controls. An autogenous Moraxella bovis bacterin (formalin-killed, whole cells) was given IM at birth and at approximate intervals of 2 weeks for a total of 3 doses. Bacterial isolation rates for the cattle in groups 1, 2, and 3 during the summer were 92.6%, 92.6%, and 54.1%, respectively, and disease rates were 100%, 96.3%, and 70.6%. The rates were significantly (P less than 0.05) different between calves and cows. Vaccination of calves at birth permitted serum antibodies to develop before the calves were extensively exposed to infection; however, immunity to the disease did not develop. In a treatment study of other animals in the same herd, but in another pasture, the same criteria were used for allocation of 107 cow-calf pairs. Eye spray was applied to treated principals (group 4, 52 calves; and group 6, 53 cows) each week after examination and sample collection. Controls consisted of 54 calves (group 5) and 54 cows (group 7) that were examined and cultured bacteriologically in the same manner. The bacterial isolation and disease rates were less (P less than 0.05) in the treated calves (group 4) than in the nontreated controls (group 5). The differences in bacterial isolation rates between groups 6 and 7 were not significant, but group 6 had less (P less than 0.05) grade III lesions than did group 7. Weekly treatment appeared to be more effective in reducing the incidence of disease than did vaccination.