MORTALITY OF DAIRY-COWS IN AN ECOPATHOLOG ICAL SURVEY IN BRITTANY

Although rare, natural death in dairy cows represents a serious econom ical loss. In a sample of intensive dairy farms, the mean yearly morta lity rate was estimated to be 0.96%. There were various causes known ( metabolic, accidental, calving-related, respiratory) and unknown (1/3 of the cases). No significant annual or seasonal variation was observe d, although the beginning of the grazing period seemed to be associate d with a higher mortality rate. The cows with a parity of 7 or more ha d a higher probability of dying (mortality rate: 3.5%). The post-partu m period was also associated with a higher number of deaths. The inter herd variability was significant, with mortality rates running between 0 and 4.24%. Nutritional diseases, digestive disorders and trauma wer e predisposing factors of natural death.