Multi-Breed Genetic Evaluation Part 5
The Base is Set
Part 5 of a Series
The ASA Board of Trustees has made a decision regarding the base for the MBE Genetic Evaluation to implemented in June, 1997 for the Fall 1997 Sire Summary. They considered several different options for defining the base using the estimated gene effects from the MBE analysis: 1) Average Angus genes in 1991; 2) Average of Simmental, Angus, Hereford, and Brahman genes in 1991; 3) Average British genes in 1991; 4) 1986 Purebred Simmental; and 5) Average of twelve gene effects in 1991. The base chosen by the Board for the weight traits is the average Simmental, Angus, Hereford, and Brahman genes in 1991.
In table 1, the average EPDs for purebred Simbrah and Simmental calves born in 1996 are listed for the Spring '97 evaluation and the MBE Research Run using the current 1986 base and the base approved by the ASA Board. For Simmental breeders, the MBE EPDs will be higher for all traits compared to the PBE EPDs. Breeders can anticipate a 3 lb. increase in BWT EPD, 19 lb. increase in WWT EPD, 35 lb. increase in YWT EPD, 8 lb. increase in MMK EPD, and 21 lb. increase in MWW EPD due to setting the base using the average of Simmental, Angus, Hereford, and Brahman genes in 1991.
Regardless of the base chosen for the MBE system, the Simbrah EPDs are comparable to the Simmental EPDs. Compared to the Spring 1997 Simbrah evaluation, the Simbrah EPDs will be different since the MBE system uses the Simbrah animal's complete pedigree. The MBE system uses the difference between the average Simmental and Brahman genes in the ASA data to adjust the EPDs. Using the MBE system, the average purebred Simbrah calf born in 1996 is about 1 lb. heavier for BWT, 11 lb. lighter for WWT, 22 lb. lighter for YWT, 2 lb. lighter for MMK, and 8 lb. lighter for MWW. The differences between Simmental and Simbrah are the same regardless of the base.
Why the 1991 Four Breed Base?
During the last two months, the ASA and CSA Boards approved the combining of the U. S. and Canadian data files into a single North American evaluation. The final research run with the MBE system is being performed using the combined data from the American Simmental and the Canadian Simmental Association. Once this research run is completed, we will have the final look at the planned changes to the EPD system prior to the Fall '97 evaluation.