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Title: Technical Note: Adaptation of an Animal-Model Method for Approximation of Reliabilities to a Sire-Maternal Grandsire Model

Author
item Wiggans, George
item TSURUTA, S - UNIV OF GEORGIA
item MISZTAL, I - UNIV OF GEORGIA

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2008
Publication Date: 10/1/2008
Citation: Wiggans, G.R., Tsuruta, S., Misztal, I. 2008. Technical Note: Adaptation of an Animal-Model Method for Approximation of Reliabilities to a Sire-Maternal Grandsire Model. Journal of Dairy Science. 91(10):4058-4061.

Interpretive Summary: A method of estimating reliability (accuracy) of genetic evaluations from animal models was adapted for use with sire-maternal grandsire (MGS) models, which are widely used for calving traits. An indication of evaluation accuracy was needed for routine use of evaluations by the dairy industry. The animal-model procedure was modified to use MGS pedigree information in place of dam information. The revised program will be used routinely in calculating reliabilities of USDA evaluations for calving traits.

Technical Abstract: The ACCF90 computer program, which approximates reliability for animal models, was modified to estimate reliabilities for sire-maternal grandsire (MGS) models. Accuracy of the approximation was tested on a calving-ease data set for 2,968 bulls for which the inverse of the coefficient matrix could be obtained. Correlations between estimated and true reliabilities ranged from 0.984 to 0.998 for first- and later-parity calving ease for sire and MGS effects. Without modification, the program treated MGS data as though they were dam data, which resulted in overestimated reliability. When pedigree data were ignored, reliability was underestimated. Correlations with true values were lower for both of those cases when compared with correct processing of MGS data. The modification provided a slight improvement over assuming MGS to be unknown. The modified program will be used for routine USDA evaluation of calving traits.