Estimation & Prediction

Approximating the theoretical accuracy for Functional Longevity in Angus Cattle

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Abstract

Accuracy is a key metric for determining how intensively animals are used in beef cattle breeding programs. Functional Longevity (FL), defined as the number of calves produced between 2 and 10 years of age, was recently implemented in the American Angus Association genetic evaluation and reflects reproductive efficiency. Direct computation of individual accuracies from the inverse of the mixed model equations is not feasible for large datasets and requires approximation algorithms such as GS2 and GS3. This study compared BIF accuracies obtained from GS2 and GS3 with benchmark accuracies derived from the exact inverse. The dataset included 396,344 animals (40,000 genotyped) and 504,689 FL records from 141,971 cows. Two models, random regression (RR) and repeatability (Rep), were evaluated. Comparisons focused on 32,000 genotyped young animals without records, representing selection candidates. Approximations were evaluated using regression coefficients, mean squared error (MSE), and Pearson's correlation coefficient. For the RR model, GS2 and GS3 produced identical results (β₀ = 0.08; β₁ = 0.93; r = 0.91). In the repeatability model, GS3 showed higher correlation (r = 0.95) than GS2 (r = 0.87), along with lower MSE. Overall, GS3 provided accurate approximations across models, with simpler implementation in the RR model, supporting its application in large-scale genetic evaluations.

Keywords: 2026

How to Cite:

Bermann, M., Garcia, A., Lourenco, D., Ramos, P., Retallick, K. & Romeiro de Lima, A., (2026) “Approximating the theoretical accuracy for Functional Longevity in Angus Cattle”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2287229. doi: https://doi.org/10.31274/wcgalp.24242

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