Mortality risk factors for calves entering a multi-location white veal farm in Ontario

Abstract Text: Mortality in pre-weaned dairy breed calves of both sexes represents a potential welfare issue and a source of economic loss for the industries involved.  While morbidity and mortality in veal production has been described, this work reflects a wide range of management practices and requirements throughout the world.  In pre-weaned dairy heifers, rates of morbidity and mortality can also range dramatically, due in large part to differing management strategies.  It has been over two decades since mortality in veal calves in Ontario was last described. The objective of this retrospective cohort study was to determine if recorded on-arrival data collected from a large white veal farm could be used as predictors of mortality.  Data was collected from 10 910 calves entering seven barns of a single white veal farm, all locations of barns within Ontario, from January 1 to December 31, 2014.  Calves were followed until death or marketing; no calves were culled during the year.  Three logistic regression models were used to determine the effects of weight on arrival, season of arrival, supplier, sex, barn and standardized purchase price on the risk of overall mortality, mortality in the first 21 days after arrival, and mortality after the first 21 days.   In the overall mortality model, significant associations (P < 0.05) were seen with season, barn, supplier and weight, with lighter weight calves arriving in winter being at increased odds of mortality.  The early mortality model contained significant (P < 0.05) associations with weight, season, barn, supplier and tended (P < 0.10) to have an association with standardized price; lighter weight calves arriving in winter at lower prices were at increased odds of mortality.  The late mortality model had significant (P< 0.05) associations with season of arrival, barn and supplier.  While not a proxy for body condition, increased weight on arrival being protective for early mortality may have somewhat reflected this, as the distribution of weights was fairly tight and likely represented calves at a week of age or less.  Although failure of passive transfer is a significant risk factor for mortality, the seasonal association we saw could reflect early life nutrition stress as opposed to seasonal variation in passive transfer.  A further exploration of dairy farm of origin risk factors for veal calf mortality may serve to improve the productivity and welfare of dairy calves of both sexes.

Keywords: Calf, mortality, veal