Hostname: page-component-78c5997874-4rdpn Total loading time: 0 Render date: 2024-11-19T22:38:51.976Z Has data issue: false hasContentIssue false
  • English
  • Français

Repeatability and bias of estimated breeding values for dairy bulls and bull dams calculated from animal model evaluations

Published online by Cambridge University Press:  02 September 2010

P. Uimari  and
E. A. Mäntysaari
P. Uimari
Affiliation:
Department of Animal Breeding, Agricultural Research Centre, SF-31600 Jokioinen, Finland
E. A. Mäntysaari
Affiliation:
Department of Animal Breeding, Agricultural Research Centre, SF-31600 Jokioinen, Finland
Get access

Abstract

An animal model and an approximative method for calculating repeatabilities of estimated breeding values are used in Finnish dairy cow evaluation. Changes in estimated breeding values over time as daughters accumulate were studied. Special emphasis was given to the accuracy and potential bias in the pedigree indices of young sires. The data set used was the same as in the national evaluation and the traits investigated were protein yield and somatic cell count. The average repeatability in evaluation of bulls without daughters was 0·37. The empirical repeatability defined as a squared correlation between the pedigree index and the final sire proof was only 0·15. The reduction in the repeatability was attributed to the selection on pedigree index. The upward bias observed in pedigree indices was 5 kg (approx. 0·3 of genetic standard deviation). The bias was caused by the overestimation of bull dams' breeding value. Also the proofs of bull sires increased after the second crop of daughters. The correlation between the evaluations of the same sire calculated from two separate equal size daughter groups was 0·91 when the bull had 10 to 50 daughters and 0·87 with over 100 daughters. This illustrates how the relative weight of the pedigree decreases while more progeny information is accumulated in the evaluation.

Keywords

dairy cattlemilk protein yieldrepeatabilitysire evaluation
Type
Research Article
Information
Animal Production , Volume 57 , Issue 2 , October 1993 , pp. 175 - 182
Copyright
Copyright © British Society of Animal Science 1993

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Brotherstone, S. and Hill, W. G. 1986. Heterogeneity of variance amongst herds for milk production. Animal Production 42: 297–303.Google Scholar
Ferris, T. A., Schneider, J. C. and Mao, I. L. 1990. Relationship between dam's age at bull's birth and bull's genetic evaluation. Journal of Dairy Science 73: 1327–1336.CrossRefGoogle ScholarPubMed
Ferris, T. A. and Wiggans, G. R. 1991. Accuracy of animal model parent evaluations in predicting daughter yield deviations for Al sampled bulls. Journal of Dairy Science 74: suppl., p. 265 (abstr.).Google Scholar
Graham, N. J., Smith, C. and Gibson, J. P. 1991. Investigation of preferential treatment for milk yield in Canadian Holsteins. Canadian Journal of Animal Science 71: 21–27.CrossRefGoogle Scholar
Henderson, C. R. 1973. Sire evaluation and genetic trends. Animal breeding and genetics symposium in honor of Dr Lush, August 1972, Iowa, USA.CrossRefGoogle Scholar
Jansen, G. 1987. Herd effects, fixed or random? Proceedings of thirty-eighth annual meeting of the European Association of Animal Production vol. 1, pp. 172–173 (abstr.).Google Scholar
Mäntysaari, E. A. and Strandén, I. 1991. Animal model evaluation for production and reproduction traits in Finnish dairy cattle. Proceedings of forty-second annual meeting of the European Association for Animal Production vol. 1, pp. 96–97 (abstr.).Google Scholar
Mao, I. L., Dong, M. C. and Meadows, C. E. 1991. Selection of bulls for progeny testing using pedigree indices and characteristics of potential bull-dams' herds. Journal of Dairy Science 74: 2747–2756.CrossRefGoogle ScholarPubMed
Meyer, K. 1989. Approximate accuracy of genetic evaluation under an animal model. Livestock Production Science 21: 87–100.CrossRefGoogle Scholar
Misztal, I. and Wiggans, G. R. 1988. Approximation of prediction error variance in large-scale animal models. Journal of Dairy Science 71: suppl. 2, pp. 27–32.CrossRefGoogle Scholar
Nicholas, F. W. and Smith, C. 1983. Increased rates of genetic change in dairy cattle by embryo transfer and splitting. Animal Production 36: 341–353.Google Scholar
Pedersen, G. A. 1991. Realized efficiency of bull dam selection in dairy cattle breeds. Proceedings of the forty-second annual meeting of the European Association for Animal Production vol. 1, pp. 142–143 (abstr.).Google Scholar
Robertson, A. 1977. The effect of selection on the estimation of genetic parameters. Zeitschrift fur Tierzuchtung und Zuchtungsbiologie 94: 131–135.CrossRefGoogle Scholar
Robinson, G. K. and Jones, L. P. 1987. Approximations for prediction error variances. Journal of Dairy Science 70: 1623–1632.CrossRefGoogle Scholar
Rothschild, M. F., Douglass, L. W. and Powell, R. L. 1981. Prediction of son's modified contemporary comparison from pedigree information. Journal of Dairy Science 64: 331–341.CrossRefGoogle Scholar
Ufford, G. R., Henderson, C. R. and Van Vleck, L. D. 1979. An approximate procedure for determining prediction error variances of sire evaluations. Journal of Dairy Science 62: 621–626.CrossRefGoogle Scholar
Ugarte, E., Alenda, R. and Carabano, M. J. 1992. Fixed or random contemporary groups in genetic evaluations. Journal of Dairy Science 75: 269–278.CrossRefGoogle Scholar
VanRaden, P. M. and Freeman, A. E. 1985. Rapid method to obtain bounds on accuracies and prediction error variances in mixed models. Journal of Dairy Science 68: 2123–2133.CrossRefGoogle Scholar
Vinson, W. E. 1987. Potential bias in genetic evaluations from differences in variation within herds. Journal of Dairy Science 70: 2450–2455.CrossRefGoogle ScholarPubMed
Weller, J. I., Norman, H. D. and Wiggans, G. R. 1985. Estimation of variance of prediction error for best linear unbiased prediction models with relationships included. Journal of Dairy Science 68: 930–938.CrossRefGoogle Scholar
Wilhelm, A. E. and Mao, I. L. 1989. Relationship between characteristics of herd of bull-dams and predicting transmitting ability of young bulls. Journal of Dairy Science 72: 2395–2401.CrossRefGoogle Scholar