Calf Health Traits
Calf health traits like diarrhea and respiratory disease are now recognized as genetically important. These economically relevant traits can now be selected for in breeding programs. This will allow dairy farmers to select for animals that are not only high-producing but also more resilient to disease as calves. Ultimately this knowledge will result in management practices that will facilitate milk and reproduction performance over the animal’s lifetime.
Genetic reasons calf health matters
Calf diarrhea and respiratory disease have non-zero heritabilities, which means they respond to selection over generations. I don't want to discount good management, but with each calf crop, farmers can gradually shift their herds’ DNA toward lower disease risk.
Calf health traits are genetically correlated with survival, longevity, and other fitness traits. They influence how many heifers actually make it to first calving and how long they stay in the herd. Leveraging genomic information helps avoid one-sided selection for milk yield that might otherwise erode disease resistance.
Economic reasons to select for calf health
From an economic standpoint, calf diarrhea and pneumonia are among the costliest diseases for dairies because they hit young animals at a vulnerable stage and ripple through the rest of their productive life. A sick calf incurs treatment costs, higher labor, more feed to catch up, increased mortality risk, and sometimes never enters the milking herd. Those losses are especially painful when you have already invested in breeding, calving, and early-life care.
Genetic gains for calf health are permanent and cumulative, so each generation born into the herd has a lower expected disease burden. That reduces ongoing veterinary costs, cull rates, and replacement pressure. In practical terms, better calf health genetics mean more heifers survive to become producing cows, more stalls filled with productive animals, and more milk sold per heifer raised.
Links to milk production and reproduction
Early-life disease has well-documented impacts on growth, age at first breeding, and age at first calving. Calves that avoid diarrhea and respiratory disease grow faster and reach breeding weight sooner, which shortens the non-productive rearing period and gets them into the milking string earlier. That translates into more lifetime days in milk and additional lactations over an animal’s life.
Respiratory disease and severe scours can leave subtle, long-term effects such as reduced first-lactation milk yield and higher risk of early culling. By selecting sires and dams with favorable calf health breeding values producers support better reproductive outcomes.
Application and future work
While still in the early stages, health traits should be something farms can select for in both the US and Canada in the Holstein and Jersey breeds. Understanding and selection will continue to be enhanced as more data is collected. We may even see additional health traits for calves included other than just diarrhea and respiratory disease.
I am excited to see where this information will take our calf rearing programs over the next few years. These genetic tools will become more reliable as their use increases and feedback on the data is given. Better genetic decisions will translate to more profitable and sustainable herds in the years to come!
Written by: Mariah Gull, M.S.
Sources:
Mahesh Neupane, Kristen L. Parker Gaddis, Sajjad Toghiani, Asha M. Miles, Jason R. Graham, Javier F. Burchard, João W. Dürr, John B. Cole, Jeffrey R. O'Connell, Curtis P. Van Tassell, Paul M. VanRaden,
Improving dairy calf health through inclusion of diarrhea and respiratory health data into a US national genetic evaluation,
Journal of Dairy Science,
Volume 108, Issue 10,
2025,
Pages 11164-11172,
ISSN 0022-0302,
C. Lynch, E.M. Leishman, F. Miglior, D. Kelton, F.S. Schenkel, C.F. Baes,
Review: Opportunities and challenges for the genetic selection of dairy calf disease traits,
animal,
Volume 18, Supplement 2,
2024,
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ISSN 1751-7311,
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