An Approximate Procedure for Determining Prediction Error Variances of Sire Evaluations

Ufford, G.R.; Henderson, Charles; Vleck, L.D. Van

doi:10.3168/jds.s0022-0302(79)83298-1

Cited by 26 publications

(7 citation statements)

References 4 publications

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“…Under sire models the common procedures were based on the reciprocals of the diagonals of the coefficient matrix after the absorption of fixed effects to the sire equations (Ufford, Henderson and Van Vleck, 1979;Van Raden and Freeman, 1985;Weller, Norman and Wiggans, 1985;Robinson and Jones, 1987). Often the squared term of correlation, called repeatability or reliability (r 2 ), is published in sire evaluation reports.…”

Section: Introductionmentioning

confidence: 99%

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

Uimari¹,

Mäntysaari²

1993

Anim. Sci.

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Link to this article: http://journals.cambridge.org/abstract_S0003356100006772How to cite this article: P. Uimari and E. A. Mäntysaari (1993). Repeatability and bias of estimated breeding values for dairy bulls and bull dams calculated from animal model evaluations. AbstractAn 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.

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Section: Introductionmentioning

confidence: 99%

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

Uimari¹,

Mäntysaari²

1993

Anim. Sci.

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show abstract

“…How far apart the two procedures lie thus depends on the number and magnitude of the off-diagonals relative to the size of the diagonals. Because the relationship matrices used here undoubtedly have smaller diagonals and larger and more numerous off-diagonals than those of a cattle sire analysis, the prediction error variances from inversion would not be expected to be as close to those from iteration as was found by Ufford et al (1979).…”

Section: Resultsmentioning

confidence: 87%

An Evaluation of Four Procedures to Rank Centrally Tested Boars

Carlson¹,

Christian²,

Rothschild³

et al. 1984

Journal of Animal Science

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“…The model with sire-by-herd interaction was used as in (8,9). Briefly: [1] where ~ is a vector containing group solutions and the Lagrange multiplier and ~ is the vector of sire solutions.…”

Section: Methodsmentioning

confidence: 99%

“…The computing procedures for best linear unbiased prediction for the model are described in (8). The sire evaluation is defined as gi + 'sij"…”

Section: Introductionmentioning

confidence: 99%

Accuracy of First Lactation Versus All Lactation Sire Evaluations by Best Linear Unbiased Prediction

Ufford¹,

Henderson²,

Keown³

et al. 1979

Journal of Dairy Science

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An Approximate Procedure for Determining Prediction Error Variances of Sire Evaluations

Cited by 26 publications

References 4 publications

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

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

An Evaluation of Four Procedures to Rank Centrally Tested Boars

Accuracy of First Lactation Versus All Lactation Sire Evaluations by Best Linear Unbiased Prediction

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