Applications of an Animal Model in the United States Beef Cattle Industry

The theory of mixed linear models is finding widespread application in the United States beef cattle industry. At least 15 beef breeds have developed or are in the process of developing national genetic improvement programs based on best linear unbiased prediction procedures and the animal model (or reduced animal model). These 15 breeds represent over 600,000 new registrations each year. The commercial industry is moving rapidly toward acceptance of genetic values on yearling bulls from these programs. Both single trait and multiple trait analyses are conducted depending on breed and traits analyzed. All breeds have developed models for maternally influenced traits. At present, primary emphasis is on growth; however, some breeds have included such traits as calving ease and hip height. Interest is developing among breeders for genetic evaluations of carcass traits. Procedures have been developed for generating genetic values on a daily basis for young animals that are not included in the major analys is due to the time of year their records were obtained. These interim genetic values provide information between major analyses.