CDCB Introduces Genetic Evaluations for Calf Health: Revolutionizing Disease Resistance

Council on Dairy Cattle Breeding (CDCB), in collaboration with the USDA Animal Genomics and Improvement Laboratory (AGIL), has officially launched the U.S. dairy industry’s first national genetic evaluations specifically targeting early-life calf health.

Beginning with the August 2026 official genetic evaluation release, dairy producers gain access to standardized Predicted Transmitting Abilities (PTAs) for two critical health traits: Resistance to Diarrhea (DIA) and Resistance to Respiratory Problems (RSP).

These evaluations empower breeders to select for genetic disease resistance against the two primary drivers of calfhood morbidity and mortality, transitioning youngstock management from purely reactive treatment to proactive genetic selection.

Economic Necessity: Mitigating High Replacement Costs

Raising replacement heifers represents the second-highest operating cost on commercial dairy farms, superseded only by feed expenses. Bovine Respiratory Disease (BRD) and scours (diarrhea) account for the vast majority of heifer losses and veterinary interventions before first calving.

Beyond immediate mortality, severe calfhood sickness inflicts permanent developmental damage—reducing average daily gain (ADG), delaying age at first calving, and impairing first-lactation milk yield.

With current replacement heifer inventories at historically tight levels and high market valuations, preserving calf health from birth is essential for farm solvency and long-term herd productivity.

Technical Specifications: RSP and DIA Evaluated

Built upon hundreds of thousands of producer-recorded health events stored within the National Cooperator Database, the new evaluations undergo rigorous quality control modeling to isolate genetic influence from environmental management effects.

Key Technical Parameters

How to Interpret and Apply DIA & RSP on Farm

Like the national cow health traits introduced in 2018 (e.g., Mastitis, Ketosis, Metritis), DIA and RSP are expressed as Predicted Transmitting Abilities (PTAs) in percentage points.

• Larger, Positive Values Are Favorable: A bull with an RSP PTA of +3.0% is expected to sire daughters that have 3 percentage points fewer respiratory events than offspring from an average sire (0.0%) when managed in the same environment.

• Population Variation: In Holsteins, active A.I. sires span a range from roughly -6.9% to +3.5% for RSP, demonstrating significant room for genetic selection despite low heritability.

• Favorable Genetic Correlations: Research confirms that RSP has a strong favorable correlation with Heifer Livability (+0.38) and a positive correlation with DIA (+0.34), as well as minor positive correlations with adult Cow Livability and Productive Life.

Future Outlook & Selection Index Integration

While RSP and DIA are launched as standalone trait evaluations in August 2026, CDCB research geneticists plan to incorporate these metrics into official economic selection indexes—such as Net Merit (NM), Fluid Merit (FM), and Grazing Merit (GM)—during upcoming formula revisions.

By incorporating calf health into holistic breeding strategies, dairy farms can build genetic resilience against calfhood disease while reducing reliance on antimicrobial treatments.