Interpretive Summary: Risk factors associated with animal mortality in pasture-based, seasonal-calving dairy and beef herds
By: Megan LaFollette
In January 2018, Journal of Animal Science published an article that investigated the risk factors associated with animal mortality in pasture-based, seasonal-calving dairy and beef herds. Mortality, or death, of animals is a concern to producers, policy-makers, and consumers alike as it impacts productivity and reflects animal welfare, including animal health. If risk factors for mortality can be identified, it may be possible to change animal management or conduct research to reduce animal mortality. Previously, risk factors associated with mortality on cattle have been investigated, but these studies have mostly been short-term and focused on dairy herds. The objective of this study was to focus specifically on pasture-based, seasonal-calving dairy and beef herds across ages to identify risk factors associated with mortality.
In this study, 4,404,122 records were evaluated from 1,358,712 cattle in the Republic of Ireland between 2008 and 2015. To analyze the data male and female cattle were split into 7 life stages and females with more than 1 calving event were stratified into 5 life stages based on parity. Risk factors that were investigated included lactation stage, seasonal factors, heterosis and recombination, calving assistance, twin births, gender, gestation length, dam parity, age at first calving, stillbirths of the dam, calving period factors (herdmates, timing, length), and herd factors (size, rate of expansion).
Multiple risk factors associated with mortality were identified for young animals and cows. Young animals and cows were more likely to die if they required veterinary assistance at their birth or calving, were a twin or produced a twin, were produced by a dam who previously had a still birth or had a stillbirth, or were a male or produced a male. For young dairy animals, the greatest mortality risk by life stage occurred between 31 and 182 days of age, which could have been a result of weaning and the corresponding diet and environmental changes. Being born after both short and long gestations were associated with an increased mortality risk. Cows were more likely to die in the first week postparturition than other times. Both young animals and cows were more likely to die in larger herds. On the other hand, having a narrow calving window decreased mortality risk in both dairy and beef calves and cows. Additional risk factors can be found in the article.
Overall, this study suggests that risk factors associated with mortality are mostly the same for both dairy and beef herds in pasture-based, seasonal-calving systems. The factors identified in this study are similar to those reported from past studies of confinement, non-seasonal-calving herds. Producers are recommended to either cull or allocate greater resources to cows that produce stillborn calves to reduce mortality rates. To minimize animal mortality in young cattle and cows, producers and researchers could use also use these results to prioritize attention and resources to cows requiring veterinary attention during birth, twin-bearing cows, and cows carrying males as well as their offspring.
To view the full article "Risk factors associated with animal mortality in pasture-based, seasonal-calving dairy and beef herds," visit the Journal of Animal Science.