December 2024 CDCB Evaluations: What’s New?
Written by CDCB
November 01, 2024
The CDCB and USDA AGIL team describes changes implemented for the triannual genetic evaluations on December 3, 2024, including updated calculations for Residual Feed Intake, integration of foreign evaluations with the new Rear Teat Placement in Brown Swiss, and exclusion of some crossbred animals in Net Merit $ trends.
Updated calculation for Residual Feed Intake (RFI)
By Kristen Gaddis and John Cole
As of the December 2024 evaluation, a minor update was made to the calculation of Residual Feed Intake (RFI). This update increased the coefficient used for protein in calculating milk energy content from the previous 5.63 to 5.85, reflecting current industry standards (Nutrient Requirements of Dairy Cattle, 8th ed., NASEM, 2021). Milk energy is one of the energy sinks factored when calculating RFI, along with metabolic body weight and change in body weight. Correlations between RFI values and Predicted Transmitting Abilities (PTAs) were greater than 0.999, comparing the original and updated protein coefficients. The maximum change in RFI PTA was -2.8, while only 16 animals had a change larger than 1. Thus, minimal impact on evaluations is expected. This update was necessary to maintain equivalence with current nutrition standards.
Net Merit Dollars (NM$) trends excluding crossbred animals
By Ezequiel L. Nicolazzi and Paul VanRaden
The Net Merit Dollars (NM$) trends for all breeds will exclude animals with missing breed codes for the sire and crossbred animals (by considering a cutoff heterosis value of 50%). A test run based on the August 2024 evaluation shows a more stable NM$ trend for Ayrshire and Milking Shorthorn, and the change does not affect NM$ trends in other breeds.
Brown Swiss Rear Teat Placement international evaluations
By Ezequiel L. Nicolazzi, Rodrigo Mota, Gary Fok and Paul VanRaden
The Brown Swiss Rear Teat Placement (RTP) evaluations, first published in August 2024, were successfully submitted for the September 2024 Interbull test run. As a result, starting in December 2024, U.S.-based RTP evaluations will be integrated into the international evaluation process, which will have a noticeable impact on this trait’s evaluation results. This addition will enhance CDCB genomic evaluations for Brown Swiss cattle by incorporating international RTP data. Both bull and cow evaluation files will now include MACE* evaluations when international PTA reliabilities are higher than domestic for all traits, including RTP. Additionally, an unintended flaw in bulls’ format 40 files, which prevented MACE-based Rear Teat Placement (Side View) and type composites for the Jersey breed, was identified and corrected.