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Heritability and Repeatability of Hereford Show-Ring Placing and Associated Correlations with Individual Performance Measurements and Expected Progeny Differences^1,2,

North Dakota State University⁵, Fargo 58105

⁴ To whom reprint requests are to be directed.

Abstract

Data associated with 1,531 Herefords shown at the National Western Stock Show at Denver from 1978 to 1984 were used to estimate heritability and repeatability of show-ring placing (SRP) and genetic, environmental and phenotypic correlations. The correlations were those between: 1) SRP and individual measurements (IM) taken at the time of show and available to the judges, 2) SRP and parents' SRP and IM, 3) male SRP and their individual expected progeny difference values (EPD) and 4) SRP and sire EPD. The IM were height, weight, backfat, weight per day of age and scrotal circumference. The estimation procedures were symmetric differences squared, analysis of variance and parent-offspring regression and correlation. Three similar estimates of SRP heritability averaged .39. Three similar estimates of SRP repeatability averaged .33 and suggested little effective selection for SRP based on first record and low permanent environmental variance. The phenotypic correlations indicated an individual's height (.63) had the most influence on its SRP followed by weight (.43). Genetic and environmental correlations between height and SRP averaged (three estimates) .78 and .37, respectively. Dam SRP, height and backfat had higher correlations with offspring SRP than those of the sire. Male SRP was moderately correlated with EPD values for weaning (.25) and yearling (.38) height and weaning (.33) and yearling (.32) weight. The correlations between SRP and sire EPD values were: .27 (birth weight), .16 (weaning weight), .33 (weaning height), .10 (yearling weight), .23 (yearling height) and .07 (maternal breeding value). The results did not support SRP as a criterion for improving growth performance traits. There was clear evidence that the show-ring placing criteria were the same for males and females. The medium value of SRP heritability indicated that placing the cattle in the show-ring was definitely not a random process, i.e., the criteria for placing the animals were probably fairly consistent over the 6 yr.

¹ Published with the approval of the Director of the North Dakota Agr. Exp. Sta. as Journal Article No. 1471.

² The authors thank the Amer. Hereford Assoc. for providing the data of this paper.

³ Current address: USDA Crop and Livestock Reporting Serv., Stephens Fed. Bldg., Suite 320, 355 East Hancock Ave., Athens, GA 30613.

⁵ Anim. and Range Sci. Dept.