Oded Nir (Markusfeld), Consultant for SAE Afikim and "Hachaklait" Mutual Society for Cattle Veterinary Services in Israel Ltd.
Diseases are multifactorial and call for a "multifactorial approach"
Most production and infectious diseases are multifactorial as well illustrated in Figure 1 that describes the associations among postparturient diseases and traits in terms of summary odds ratios.
TWIN=twins; STILL=stillbirth; PRO=prolapsed uterus; MF=milk fever; MET=primary metritis; RP=retained placenta; ACID=aciduria; KET=ketosis; LDA=left displacement of the abomasum (after Markusfeld, 1987)
Figure 1. Interrelationships among calving traits in terms of odds ratios (8521 lactations)
Control of Production Diseases often involves various disciplines and therefore calls for a "multivariate approach". Such an approach, centered on the herd, had led to the adaptation of integrated programs of herd health. Details of the Israeli Program are found elsewhere (Markusfeld-Nir 1996).
To cross the line from individual to herd medicine, data should be recorded and processed, so that both statistical and epidemiological evaluations can be carried out. Herd health monitoring is done on populations, not on individuals. Individual cow data are yet essential if interactions between factors are to be clarified. Achieving optimal cow performance by drawing operational conclusions from data is the ultimate aim of such a program.
Herd health analysis, has been continuously evolving process, in which we addressed the following questions: what happened → why it happened → what were losses in production and fertility → how much did it cost us?