To incorporate new findings and enhance accuracy of evaluations, CDCB and USDA AGIL announce several updates for the triannual genetic evaluations on August 13, 2024.
Detailed in this post by CDCB and USDA AGIL, the August changes include:
- 305-AA is the new standardized yield measurement: 305-AA replaces 305-ME in the calculation of CDCB genetic evaluations, effective in August 2024. Since mid-June 2024, the 305-AA yield estimates have been available for individual animals through CDCB WebConnect queries. As 305-AA is based on recent analysis in the modern dairy environment, this change enables fairer phenotypic comparisons of standardized records for cows of different ages, parities and seasons of calving.
- Constructed IDs: August 2024 marks the first triannual evaluations with full implementation of Constructed IDs across the entire CDCB database. The full implementation has been included in monthly and weekly evaluations since July 2, 2024 (as previously communicated). Constructed IDs use parentage identification via genomics to build more complete pedigrees for animals that previously had no link to their maternal ancestors, increasing evaluation accuracy. Read more below.
- Heifer Livability: Edits and modeling were improved for Heifer Livability (HLV), which will greatly improve HLV evaluations for bulls whose daughters were in the last two years of data and genomic predictions for progeny of those bulls.
- Rear Teat Placement in Brown Swiss: Rear Teat Placement (RTP) is available in August 2024 traditional and genomic evaluations for Brown Swiss. Traditional evaluations – those produced from only performance data – include RTP as a single trait, currently uncorrelated to other traits. These values then provide an RTP evaluation to all 72,000-plus genotyped Brown Swiss animals.
- New SNP list: The set of 78,964 genetic markers, gene tests and quantitative trait loci used in genomic predictions since 2021 was updated to a new list of 69,200 SNPs. This revision starting in August 2024 has very limited impact on evaluations and will allow focus on the most impactful and new markers, while improving system processing time. Markers removed had small effects on traits, were not on recent chips, or had poorer genotype quality. Also, five new gene tests were added. The SNP list revision may affect carrier status for a slightly higher percentage of animals, because some haplotypes now include a different set of markers.
- Annual Breed Base Representation (BBR) update: The 2024 update is effective in August (rather than April as previously), to use the new set of 69,200 SNPs. The test run showed comparable results to previous annual BBR changes, confirming the limited effect of the decluttered SNP list.
- HH6 and JNS gene tests in haplotype calculations: Holstein HH6 and Jersey Neuropathy with Splayed Forelimbs (JNS) will now include direct gene test information in their haplotype calculation.