Herd factors associated with dairy cow mortality

Area of Science:

• Veterinary epidemiology
• Animal science
• Dairy production management

Background:

• Rising dairy cow mortality rates present a significant challenge to the US dairy industry.
• Understanding the multifactorial causes of dairy cow death is crucial for improving herd health and sustainability.

Purpose of the Study:

• To investigate associations between herd management practices, disease occurrence, and mortality rates on US dairy operations.
• To identify specific risk factors contributing to increased dairy cow death rates.

Main Methods:

• Analysis of the National Animal Health Monitoring System's Dairy 2007 survey data from 459 US dairy operations.
• Utilized univariable and multivariable regression models to assess relationships between mortality and 162 management/characteristic variables.
• Focused on factors including vaccination, disease testing (bovine leukosis virus), postmortem evaluations (necropsies), and clinical conditions (mastitis, infertility, lameness).

Main Results:

• Heifer vaccination against specific diseases was associated with a 32.0% decrease in mortality.
• Positive bulk tank milk ELISA for bovine leukosis virus was linked to a 27.0% increase in mortality.
• Increased mortality correlated with the use of necropsies, higher proportions of cows with clinical mastitis, infertility, and lameness.

Conclusions:

• Dairy cow mortality is influenced by reproductive issues, postpartum diseases, infectious disease prevention, and postmortem diagnostic information.
• Effective management strategies addressing these diverse risk factors are essential to mitigate excessive mortality in dairy herds.
• Targeted interventions, including vaccination and improved diagnostic approaches, can help reduce dairy cow death rates.