Cointegration analysis used in a study of dairy-cow mortality.

A competitive environment forces the farmer constantly to adopt new and more-intensive production methods aiming at lowering costs and increasing yields. At debate is whether this intensification of production has an adverse impact on animal health and welfare. We investigated this issue by using cointegration analysis (a new tool used in time series analysis). We introduce cointegration analysis by applying the method in an epidemiological study of dairy-cow mortality. Two long-run epidemiological relations are identified:(i) a physiological relation (where increasing consumption of concentrates corresponded to increasing milk yield and mortality) and (ii) a physical relation (which illustrated that higher mortality was closely related to a higher growth rate of the average herd size, current investments in dairy farming, and higher milk yield). We concluded that a higher level of physiological stress due to higher yield and concentrate consumption has led to increased mortality. Furthermore, changes in the physical environment due to increased mechanisation and larger herd sizes have contributed to less attention per cow and increased mortality.