A field study of culling and mortality in beef cows from western Canada.

The objectives were to describe the pattern of losses through culling, sales of breeding stock, mortality, and disappearance, and to characterize the causes of mortality of cows and replacement heifers of breeding age from Western Canadian beef herds. Cows and replacement heifers from 203 herds were observed for a 1-year period starting June 1, 2001. Veterinarians examined dead animals on-farm using a standard postmortem protocol. The incidence of culling in cows and replacements heifers was 14.3 per 100 cow-years at risk, and the frequencies of sales for breeding stock, mortality, and cows reported missing per cow-years at risk were 4.0, 1.1, and 0.4, respectively. During the study, 355 animals died or were euthanized, 209 were examined postmortem, and the requested tissues were submitted for histopathologic examination from 184. A cause of death was determined for 70% (128/184) of the cows with complete gross postmortem and histopathologic examinations. Hardware disease (traumatic reticuloperitonitis), malignant neoplasia (cancer), calving-associated injury, rumen tympany (bloat), myopathy, and pneumonia accounted for 56% (72/128) of the animals where a cause of death was determined. Twenty-three other causes of death accounted for the remaining 44% (56/128). Factors relating to cow nutrition accounted for 25% of the deaths, emphasizing the importance of feeding management as a determinant of cow health in western Canada.