What to Expect for Calving Ease Base Change in August 2025:
In April 2025, the dairy industry had a proof run that brought many significant changes because of the new base change. One area that did not see adjustments in April was Calving Ease. Now that the August proofs are quickly approaching, the CDCB has released what we can expect when it comes to Calving Ease.
Within the Holstein breed calving ease has significantly improved. In August 2025 the Brown Swiss and Holstein Breeds will undergo a genetic base change. This delay in the base change was due to unexpected results but after being reviewed, the calculations are reviewed and ready to be released. Calving ease and stillbirth traits are evaluated using a sire-maternal grandsire threshold model. This model estimates the likelihood of difficult calvings or stillbirths by separating genetic influence which breeders can select for, from environmental factors, such as feeding and gestation management. Since environmental conditions affect calving outcomes, they are factored into the Predicted Transmitting Ability (PTA). For example, daughters of a sire calving in less favorable environments will likely show more difficult births, while those in better-managed settings tend to have easier calvings.
With the new base adjustments, Holstein PTAs will shift to reflect about a 0.8% decrease in difficult calvings indicating genetic improvement. In contrast, Brown Swiss PTAs will show an increase of approximately 0.6% in calving difficulty, suggesting less favorable recent trends in this breed. We look forward to seeing these results and the progress that both breeds will make in the near future!
Here are some more updates you can look forward to seeing how the bases will be set:
Sire calving ease (SCE) = Predicts the tendency of service sires to produce offspring that are delivered easily, expressed as the percentage of births of calves coded “difficult” for first calf (primiparous) heifers compared to other A.I. bulls born in the reference year. Beginning in August 2025, this is set to 2020.
Daughter calving ease (DCE) = Predicts the tendency of the daughters of sires to have offspring that are delivered easily, expressed as the percentage of births of calves that are “difficult” in first calf (primiparous) heifers compared to other A.I. bulls born in the reference year. Beginning in August 2025, this is set to 2015.
Sire stillbirth (SSB) = Predicts the tendency of service sires to produce offspring that are stillborn (dead at birth or within 48 hours of birth), expressed as percent compared to other A.I. bulls born in the reference period. Beginning in August 2025, this is set to 2020.
Daughter stillbirth (DSB) = Predicts the tendency of the daughters of sires to have offspring that are stillborn (dead at birth or within 48 hours of birth), expressed as percent compared to other A.I. bulls born in the reference period. Beginning in August 2025, this is set to 2015.
CDCB Explanation of Changes:
https://uscdcb.com/calving2025