Culling is a valuable tool to improve the profitability of the dairy herd. Under preferred circumstances, producers limit involuntary culling (reproductive failure, mastitis and udder, feet and legs, disease or injury, and death) to be able to cull for voluntary reasons (dairy and low production).
Death is obviously the most undesirable category of involuntary culling. Mortality results in an animal with no salvage value and disposal can be inconvenient and costly. Mortality takes away the opportunity to remove an animal for other purposes and increases the need for replacements, both of which negatively impact a herd’s finances.
A recommended goal for cow mortality is to keep death loss less than 2% annually. DairyMetrics data from Dairy Records Management Systems in September 2015 showed that an average of 5.7% of cows die every year in Virginia dairy herds. Nationally, the Council on Dairy Cattle Breeding reported that 5.5% of lactations in 2014 ended due to the death of the cow. The National Animal Health Monitoring System (NAHMS) Dairy 2007 project found that 5.7% of cows died annually in the surveyed herds. Virginia death losses are comparable to national averages, but have room for improvement.
Tracking mortality in a dairy herd can be done through DHI records, dairy management software (PCDART, DairyComp, parlor management software), and/or spreadsheets. Knowing a herd’s mortality rate is an important first step in determining whether a manager should be alarmed, but it does not tell the whole story.
The adage, “If you don’t measure it, you can’t manage it,” applies to mortality information. If used in conjunction with health records, mortality information may provide supplemental data to identify problem areas in herd management. Identifying and recording the cause of death should be standard procedure. Necropsies should be performed when the cause of death is not immediately known. Troubleshooting problems can be much easier if the herd manager is recording the cause of death. According to NAHMS Dairy 2007, the top three causes of death in dairy cows were: lameness or injury (20.0%), mastitis (16.5%), and calving problems (15.2%). Next was “unknown”(15.0%), highlighting the need for more information in many instances.
Examining the stage of lactation and seasonal patterns of mortality can prove useful. For example, if death losses are highest in the first 60 days of lactation, the manager should closely examine transition cow management. If losses are much higher during the summer months, the manager should consider improving heat abatement for groups most affected.
The Herd Summary DHI-202 report indicates the number of cows that die annually by lactation number and the number that die during test intervals. DHI herds can request to receive the Survival Analysis DHI- 232 report from Dairy Records Management Systems. This executive report identifies the number of deaths in first and second lactations by days in milk. It does not report the cause of death, however. In smaller herds (<200 cows), it may be more difficult to identify trends because of a smaller number of observations.
Herd managers should work closely with their veterinarian to develop and routinely evaluate a comprehensive herd health program with emphasis on prevention and early detection. Morbidity and mortality should be monitored. The data provided by precision dairy tools (pedometers, accelerometers, rumination monitors, etc.) may be useful to producers in improving overall health of the herd and in reducing morbidity and mortality rates. Technologies should be evaluated on their practicality, precision, accuracy, and cost effectiveness before being purchased.
Source: Virginia Cooperative Extension
