Dairy calf mortality rate: influence of meteorologic factors on calf mortality rate in Tulare County, California.

Monthly calf mortality data for a period of 5.5 years in Tulare County, California, were compared with monthly summarized weather data for that county, using multivariate statistical techniques. In winter, increases in the calf mortality rate (CMR) were significantly associated with cold, wet, windy weather; in summer, greater death losses were associated with hot, dry weather. In general, the calf losses in winter seemed more closely related to weather phenomenon than those in summer. The CMR during a 6-month period (July to December, 1973) were predicted, using equations containing data on the more important weather variables. The predicted CMR significantly differed from the observed death rate during July through September. During October through December, the predicted and observed CMR did not significantly differ. An increase in mortality rate was not predicted for winter, mainly because of low rainfall, and none occurred.