Illustration of the maternal animal model used for genetic evaluation of beef cattle

¹ Agriculture and Agri-Food Canada Research Centre, Lethbridge, AB T1J 4B1 Canada; Dept. of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, AB T6G 2E1 Canada
² Dept. of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, AB T6G 2E1 Canada

^* To whom correspondence should be addressed. E-mail: dcrews{at}agr.gc.ca.

	Abstract

National cattle evaluation programs for weaning weight (WT205) in most beef breed associations involves implementation of the maternal animal model to predict direct and maternal EPD. With this model, direct breeding values are predicted for all animals with records and(or) pedigree ties to animals with records. Even though maternal genetic value is expressed only in animals that become dams, these effects are transmitted by all parents and inherited from parents by all animals, leading to maternal breeding values being predicted for all animals as well. A small example data set was simulated involving 12 parents, 8 non-parents and 13 animals with WT205 records. The pedigree was developed to include paternal and maternal half-sib families, full-sibs, and some inbreeding, similar to beef cattle field populations. Assembly of the mixed model equations and solutions for the maternal animal model are illustrated explicitly to assist animal breeding students in their understanding of properties of the maternal animal model, and to explicitly implement the model. Model parameters and moments, fixed contemporary group solutions, adjustment of breeding values for merit of mates, interpretation of maternal permanent environmental effect solutions, and alternatives for the assembly of the equations are shown. This example could lead to increased student and producer understanding of genetic improvement programs for weaning weight in beef cattle.

Key Words: Beef Cattle, Genetic Prediction, Maternal Animal Model, Teaching