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Multivariate Evaluation of Phenotypic Relationships between Early Performance and Subsequent Productivity in Hereford and Angus Cows¹

Oklahoma Agricultural Experiment Station, Stillwater 74705

Abstract

Records on 338 Angus cows and 1,327 progeny, and 202 Hereford cows and 826 progeny were used to evaluate principal component (PC), canonical correlation and discriminant analyses as methods to provide indications of cow productivity (calf weaning weight) from cow traits measured early in their productive life. Heifer prebreeding traits included birth weight, preweaning daily gain, 205-day weaning weight, weaning conformation score, postweaning daily gain and 425-day weight. All traits were adjusted for year, age of dam and sex. Correlations between first PC for heifer traits and first PC for progeny weaning weights ranged from .16 to .33 and .11 to .22 in Angus and Herefords, respectively. With first progeny weaning weight included as a cow trait, correlations between the third PC for cow traits and first PC for calf weaning weight were .32 to .39 and .53 to .69 in Angus and Herefords, respectively. First canonical correlations between heifer traits and progeny weaning weights ranged from .24 to .43 in Angus and from .31 to .50 in Herefords. With first progeny weaning weight included as a cow trait, first canonical correlations ranged from .47 to .59 in Angus and from .64 to .72 in Herefords. Regression of sum of calf weaning weights on heifer traits yielded multiple correlations of .24 to .3 3 and .17 to .30 in Angus and Herefords and multiple correlations from regression of MPPA for weaning weight on heifer traits were .25 (Angus) and .21 (Hereford). Regression of sum of second through seventh calf weaning weights on heifer traits and first progeny weaning weight yielded multiple correlations of .42 to .62 and .63 to .75 in Angus and Herefords. Classification by discriminant analysis into quartiles of productivity was only slightly better than chance when heifer prebreeding traits were used. Inclusion of first progeny weaning weight as a trait of the heifer improved the proportions of correct classifications substantially.

¹ Journal Article 3433 of the Agricultural Experiment Station, Oklahoma State University, Stillwater. Research was conducted by the Animal Science Department (Project 1256) in cooperation with USDA, Southern Region.

² Present address: Animal Science Department, South Dakota State University, Brookings 57007.

³ Animal Science Department, Oklahoma State University, Stillwater.

⁴ Statistics Department, Oklahoma State University, Stillwater 74075.