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Including Pedigree Relationships in Beef Sire Evaluation^1,2,

North Dakota State University^,4, Fargo 58105

Abstract

A data set was utilized to develop knowledge of the implications to single trait beef sire evaluation by best linear unbiased prediction (BLUP) of including the pedigree relationships among the sires in the evaluation procedure. The data, which consisted of 680 progeny of 61 sires obtained over 7 yr, were from the American Shorthorn Association's national sire evaluation program. One year's data did not include a reference sire. A four-generation pedigree was available for each sire. Results were obtained for the original progeny numbers per sire, when 6 and 16 progeny were added for each sire and for 11 values of heritability. Ignoring the additive relationships (a_ij) increased the measures of prediction error variance (PEV) of sire comparisons associated with a;; of .5 a small amount (6.78% averaged over 11 values of heritability). Using the sire-maternal grandsire rather than the complete pedigree increased PEV by only miniscule amounts. The best linear prediction PEV were only slightly smaller than those of BLUP. Predictions of differences between disconnected and connected sires were rendered only slightly more accurate when either the complete or sire-maternal grandsire additive relationship matrix was used. Variances of estimators of year differences were only very slightly improved. However, substantial changes in expected progeny difference (EPD) values did occur. The maximum change in rank for the six traits evaluated was 15 for weaning weight. Including the additive relationship matrix reduced the yearling weight EPD of one sire 3 kg.

¹ Published with the approval of the Director of the North Dakota Agr. Exp. Sta. as Journal Article No. 1445.

² The authors thank the Amer. Shorthorn Assoc. for allowing the data of the paper to be used for research purposes.

³ Present address: Wheaton, MN.

⁴ Anim. and Range Sci. Dept.