CDCB Publishes Two Genetic Traits for Calf Health
The Council on Dairy Cattle Breeding (CDCB) published the evaluations in August 2026. They measure predicted transmitting ability (PTA) for two diseases associated with calf mortality: diarrhea and respiratory problems. A higher positive PTA indicates that an animal is expected to pass on greater resistance to the relevant condition.
The respiratory-resistance measure, known as RSP, estimates the expected resistance of an animal’s offspring to respiratory disease during calfhood. The diarrhea measure, DIA, applies the same principle to calfhood diarrhea. The evaluations are currently available in bull proofs and female genomic test results for Holstein and Jersey cattle. CDCB said evaluations for more breeds are expected as additional data are collected.
Health and economic data
Katie Schmitt, CDCB’s industry relations manager, said diarrhea affects one in seven calves during early calfhood, while respiratory problems affect one in six. She cited estimated costs of about $25–50 for an episode of diarrhea or scours and about $40 for an episode of respiratory disease.
The two measures are not yet part of the Net Merit index, which combines economically important genetic traits to rank dairy cattle. Schmitt said a future revision of the index is expected to include them, allowing economic values to be assigned to labour and health costs associated with the conditions.
Based on the latest data, the heritability of both traits is about 2–3%. Schmitt said genetic progress remains possible for traits with relatively low heritability because gains can accumulate over time. She also said genetic selection does not replace calf management or nutrition, but can be used alongside animal care.
Records support the evaluations
CDCB’s calf measures follow the development of genetic evaluations for cow health. The US Department of Agriculture and CDCB have evaluated dairy genetic traits for years, with the first official genomic evaluations introduced in 2009 after genomic-testing chips became available in 2007. CDCB added six health evaluations for Holstein cows in 2018 before researchers developed comparable measures for calves.
Robert Fourdraine, assistant director of product development at Dairy Records Management Systems and a CDCB board member, said farms need to identify animals with unique tags and record health events across the entire herd. Such records can be analysed by age group or calendar period to identify patterns in respiratory disease, injury, lameness and other losses.
Fourdraine said the information also affects decisions about breeding dairy animals or using beef genetics. Without accurate figures for heifer losses, pregnancy losses, calf losses and stillbirths, farms may misjudge the number of replacements they will need. Schmitt urged producers to send records on both sick and healthy calves to their Dairy Records Processing Center so the information can enter the national co-operator database used to build genetic predictions.
