Resistance to Respiratory Problems (RSP)
RSP predicts the expected resistance of an animal’s offspring to calfhood respiratory problems.
August 2026 Evaluations
These evaluations will include three new traits and revisions to four existing female reproductive performance traits.
Introducing Calf Health Traits
Raising replacement animals is one of the costliest aspects of dairy production, and calfhood disease can make it even more expensive. CDCB is implementing the first national selection traits to address calf health concerns with Resistance to Respiratory Problems (RSP) and Resistance to Diarrhea (DIA).
After cow health traits were first introduced in 2018, research began on applying similar methodology to calf health. Scientists at CDCB and USDA’s Animal Genomics and Improvement Laboratory studied calf health records stored in the National Cooperator Database to uncover trends and genetic relationships. The most records were available on respiratory disease and scours, the two most common calfhood illnesses. The team developed these traits by analyzing more than 768,000 respiratory disease records in animals of all breeds between 3 and 365 days old and more than 260,000 diarrhea records in calves of all breeds between 3 and 60 days old.
Reintroducing Female Reproductive Performance Traits
Since 2003, the U.S. national evaluation system has produced traits that predict female reproductive performance. In 2024, a foundational review of this trait portfolio (Daughter Pregnancy Rate, Cow Conception Rate, Heifer Conception Rate, and Early First Calving) began because industry practices — estrus synchronization, heat detection technology, sexed and beef semen, and voluntary waiting period (VWP) shifts — have since changed the way dairy producers make and interpret reproductive decisions. Seasonal fluctuations between official evaluations, consistent downward trends in young bull PTAs, and genetic trends moving in unexpected directions all prompted the review.
Over the two-year review process, multiple solutions were tested to refine the reproductive performance traits. The research team’s work concluded with ten recommended revisions including the introduction of a new selection option, First Service to Conception (FSC):
Because on-farm tools have helped dairy farmers improve herd reproduction in the last two decades, these adjustments do a better job of separating genetic improvement from management effects. This leads to more accurate and representative genetic evaluations as we measure genetic progress more appropriately.
Explanation of Changes
Dive deeper into the research process, key findings, details about the ten changes and how to the interpret the revised traits
First Service to Conception (FSC) – NEW TRAIT!
FSC addresses the need for a selection trait calculated independently of VWP. It predicts the expected difference, in days, from first breeding to conception in an animal’s daughters relative to the breed base. Positive PTAs represent fewer days to conception.
Daughter Pregnancy Rate (DPR)
DPR predicts the expected difference, in percentage points, in pregnancy rate of an animal’s daughters relative to the breed base.
Cow Conception Rate (CCR)
CCR predicts the expected difference in conception rate of daughters as lactating cows relative to the breed base.
Frequently Asked Questions Related to Female Reproductive Performance Changes
In the previous system, some long-term changes in herd management were not fully accounted for in the model. As a result, some of the effects of management choices could be incorrectly attributed to genetics, which made trends for traits like DPR and CCR appear flat or even declining.
The updated model does a better job of separating genetic improvement from management effects and accounting for how on-farm practices have changed in the last 20 to 25 years. The change in trend does not mean biology has suddenly improved; it means we are now measuring genetic progress more accurately.
FSC is measured and expressed in days as opposed to DPR and CCR, which are expressed as a percentage. FSC also does not include VWP in its model, so it is able to capture fertility performance and account for individual cow management independently of herd-level VWP systems or changes.
DPR PTA continues to predict the expected percentage of non-pregnant cows that become pregnant during each 21-day cycle, relative to the breed base. The model used to calculate DPR was revised to account for a herd-level and lactation group-specific VWP.
CCR PTA continues to predict the expected difference in conception rate of daughters as lactating cows relative to the breed base. The model used to calculate CCR was revised to include a days-in-milk covariable with pre-adjustments to individual inseminations.
HCR PTA continues to predict the expected difference in conception rate of daughters as maiden heifers relative to the breed base. The model used to calculate HCR was revised to account for service sire breed as well as mating type and short cycling (an insemination that occurs 10 to 17 days after the previous insemination).
EFC PTA continues to predict days above or below the breed base (mean) that an animal’s daughters will calve for the first time. The model used to calculate EFC was moved to single-trait for computational efficiency.
The changes in PTA ranges, mean PTAs, and standard deviations between versions of traits are due to the updated model and variance components. These differences represent a rescaling of each trait rather than a true increase or decrease in underlying genetic variation.
DPR is best for producers who use a VWP on a herd level and want cows to cycle, get bred, and become pregnant quickly regardless of the number of services.
CCR is best for producers who want to improve conception rate success per service since it reflects how many inseminations are needed.
FSC is best for producers who apply VWPs on a cow-by-cow basis and want cows to get pregnant as quickly as possible after the first breeding.
Remember that the PTAs for these traits will look different. DPR and CCR are expressed as percentages, while FSC is expressed in days. The following PTA ranges of active A.I. bulls were produced in a test run and are expected to vary slightly as more phenotypic data becomes available.
| DPR (%) | CCR (%) | FSC (days) | |
| Brown Swiss | -1.6 to +3.0 | -3.6 to +2.9 | -7.8 to +9.2 |
| Holstein | -5.3 to +5.7 | -8.3 to +7.3 | -24.8 to +20.4 |
| Jersey | -3.6 to +5.0 | -4.1 to +5.1 | -12.5 to +15.2 |