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Sire Evaluation Methods¹

The Pennsylvania State University, University Park 16802

ABSTRACT

Lactation records of Pennsylvania Jerseys were used to compare five methods of sire evaluation. Each sire with a minimum of five daughters in at least 2 consecutive yr was in the analysis. Comparison of methods was based on the correlation of evaluations in consecutive years. The five methods compared were daughter-dam comparison, predicted difference from herdmates, predicted difference from herdmates adjusted for dams, predicted difference from contemporaries, and predicted difference from contemporaries adjusted for dams. All five methods were compared on data restricted to first-lactation daughters. The first three methods also were compared in records from all ages. By average weighted correlations between sire evaluations in consecutive years, the daughter-dam method was least satisfactory. Predicted difference from herdmates showed essentially no improvement from adjustment for dams. Predicted differences of deviations from contemporaries generally gave lower correlations than predicted differences of deviations from herdmates, presumably because of fewer stablemates in the deviations.

¹ Authorized for publication November 26, 1973 as Paper No. 4586 in the Journal Series of the Pennsylvania Agricultural Experiment Station.

² Department of Dairy Science.

³ Department of Animal Science.

⁴ Present address: Nagpur Veterinary College, P. O. Nagpur, Maharastra, India.