A group of 80 Holstein calves, many with clinical signs of infectious bovine keratoconjunctivitis in summer seasons, was assembled for bacteriologic and ophthalmologic studies at an integrated dairy farm.
Observations were started from 1980 to 1984 but bacteriological study was only carried out from thor spring in 1981 and continued during the Autumn in 1981. Corneal lesions and drugs sensitivity were also observed and the results obtained were as follows :
1. Occurrences of IBK-affected cattle during the 5 years were predominent to calves in summer.
2. Among 142 eyes from 80 cattle, 53 isolates of Moraxella bovis(37.3%) were isolated from 37 cattle(46.3%). The prevalence of the infection for clinical eyes were higher than nonclinical eyes calves.
3. Miscellaneous organisms were found from age groups of 5 months to 9 months old. It were 8 hemolytic Neisseria app., 3 Fungi, Mycoplasma sp. and 1 Pseudomonas sp., but 9 samples were unknown.
4. Prevalence of infection with M. bovis in bilateral clinical eyes were higher than unilateral eyes.
5. Incidence of corneal lesion was predominent in early stage as a watery tears(21.0%) and late stage as a leukomas of corneal opacity(22.8%).
6. The number of isolations of M.bovis and incidence of IBK varied from year to year; Higher incidence of IBK clinical signs were showed in calves from 5 months to 10 months old and the number of isolations of M.bovis was declined in order 8 months(100.0%), 4 months (75.0%), 5 months(66.6%) and 8 months(66.6%) old calves.
7. Chloramphenicol, Nitrofurantoin and Cephalothin were highly sensitive against M.bovis isolates and then Tetracycline, Neomycin, Erythromycin and Kanamycin were intermediate but low sensitive to Streptomycin, Colistin and Penicillin.
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