Pathogenesis of subclinical bovine mastitis: diagnostic and dynamic characteristics of various subclinical udder conditions monitored by means of the International Dairy Federation criteria.
This investigation, conducted on a small herd milked by machine without disinfectant teat dipping, shows that a limited population of 21 normally lactating dairy cows regularly examined at 24 h intervals during 22 consecutive days, may be used for monitoring dynamic fluctuations of udder conditions. From the results it is apparent that, on subclinical levels, udder health of dairy cows depends in principle on a variety of conditions, variability in dynamic fluctuations and the balance between persistent, deteriorating and improving health states. As health states, especially active and intermediate to the mastitic and normal condition at the opposing extremes of udder health, aseptic mastitis (AM) and latent infection (LI) cross-reacting with each other and with each of the other health states, are of particular practical interest. From the dynamic fluctuations of AM and LI it seems conceivable that the strategy of mastitis control proposed by several workers and found lacking in several respects during this investigation, may promote the shifting of abnormal udder conditions from those associated with mastitogenic infections to others of a non-bacterial, i.e. unspecific nature. In general, the data suggest that further work on the dynamics of different health states is necessary, and that it may be advantageous also to use the small herd model described for determinations on representative populations of cows selected at random from large dairy herds otherwise unsuitable for investigations on daily and other dynamic changes of udder health.
D000818:Animals; D002417:Cattle; D005260:Female; D007390:International Agencies; D008321:Mammary Glands, Animal / Q000382:microbiology; D008414:Mastitis, Bovine / Q000175:diagnosis* / Q000382:microbiology; D012015:Reference Standards