Pathogenesis of subclinical bovine mastitis: a comparison of the dynamic balances of various subclinical udder health states monitored by means of single-, double- and triple-parameter laboratory techniques.

This comparison of results from parallel investigations, conducted on the small herd model already discussed, has made it abundantly clear that during lactation, udder health as such depends on the 3 major determinants of intramammary epithelial integrity, somatic cellular defence and bacterial challenge. Different subclinical health states and related dynamic fluctuations indicate that each of these conditions and changes depends on the type of major determinant of udder health as well as on the nature and magnitude of factors challenging that determinant, either singly or in combination with another of the main determinants. Because of the involvement of 3 important determinants, diagnostic techniques must of necessity facilitate the concurrent monitoring of each of the determinants and the integrated interpretation of results generated. Such an approach to investigations into subclinical mastitis is not feasible by means of either single- or double-parameter techniques. In contrast, triple-parameter determinations capable of monitoring each of the 3 major determinants of udder health and performed during this investigation by means of the IDF/BSA (International Dairy Federation/bovine serum albumin) criteria, clearly have facilitated the interpretation of results at unprecedented levels of diagnostic differentiations. In the light of this clearer insight into a comparatively extensive range of udder health states at the subclinical level and corresponding dynamic balances and pathogenetic developments, it is apparent that appropriately designed and standardized triple-parameter techniques of high diagnostic sensitivity and reliability, would make the diagnosis of udder health states far more specific, and the control and prevention of subclinical mastitis far more cost-effective, than generally thought possible under present conditions. Further progress in research and practical work on subclinical mastitis may well depend on efficient triple-parameter techniques for determinations on persisting, deteriorating and improving states of bovine udder health.