CDCB and USDA AGIL have implemented several edits and updates for the triannual U.S. evaluations on April 4, 2023. Read the complete detail from CDCB and AGIL scientists here.
- Constructed IDs: As implementation will be gradual, the April evaluation will include a low number of Constructed IDs. A test run showed only minimal impact on evaluations overall. The animals that gain pedigree information through the Constructed ID method will receive more accurate evaluations.
- Brown Swiss Fertility Haplotype BH14: This new lethal haplotype in Brown Swiss, which causes early pregnancy loss, has been added to the genomic haplotypes reported in the U.S.
- Holstein Cholesterol Deficiency (HCD) Inheritance Update: New methods demonstrate much more accurate haplotype tests for the millions of Holsteins that have been genotyped but not gene-tested for HCD. The enhanced methodology will be first implemented in official evaluations in April, whereas the procedure will be effective immediately for weekly evaluations.
- Gestation Length edit for Unreported Embryo Transfer: A new edit for unreported embryo transfer (ET) was applied to gestation length (GL) following similar 2022 edits to sire, heifer, and cow conception rates. For the last 10 years of proven Holstein bulls, the PTA correlation was 0.998. The PTA Standard Deviation (SD) and correlation of PTA with birth year (genetic trend) did not change.
- New Edits for Heifer Livability: Heifer livability measures percentages of calves that die on the farm compared to those that live to at least 18 months. Calves that had other termination codes, or were sold, before 18 months are now deleted. The better separation of live from dead calves increased the PTA SD but had very little effect on ranking.
- Significant increase of records in health evaluations: A large number of health records have been submitted to CDCB since the December 2022 evaluation. CDCB analysis showed the largest impacts are expected for mastitis resistance (MAST) evaluations. Lower trends on MAST for younger animals were observed, especially in the Jersey population; MAST trends for older animals remained stable. PTA correlations for all other health traits were greater than 0.99.
- SNP Usability Updates and Imputation Error Rate Increase: Effective for the April 2023 evaluation is the yearly SNP usability update, which improves the performance of SNPs for newest chips. Also, imputation error rate was increased in an effort to better identify undesirable haplotypes. Neither change is expected to have noticeable impact on evaluations.
- Yearly BBR Update: The annual Breed Base Representation (BBR) update will be implemented for the April 2023 evaluation. The purpose of this routine update is to reduce monthly evaluation variation in case of large changes in the reference population.
- Exclusion of Interbull Milking Shorthorn Type Evaluations: A procedure was modified to exclude all Interbull conformation evaluations for animals with MSH breed code, to avoid different trait definitions negatively impact type evaluations in Milking Shorthorn.
- Exclusion of NZL from pedigree and PTA of foreign dam exchange: in the April 2023 evaluations, female animals previously receiving direct PTAs from New Zealand will receive Parent Averages, which will result in larger variation to their evaluations and their progeny’s evaluations.
- International Evaluations for Clinical Mastitis in Brown Swiss: The intended enhancement announced in December 2022 was not introduced. Brown Swiss foreign evaluations will be included in the April 2023 U.S. Clinical Mastitis evaluations.
