PSVIII-4 - Genetic evaluation of functional heifer longevity in North American Angus cattle

Friday, July 16, 2021

12:00 PM – 1:00 PM EST

Location: Kentucky International Convention Center, Poster Hall/North Lobby

Presenting Author(s)

Hinayah R. Oliveira

Postdoctoral Researcher
Centre for Genetic Improvement of Livestock, University of Guelph, Guelph, ON, Canada; Department of Animal Sciences, Purdue University, West Lafayette, IN, USA
Guelph, Ontario, Canada

Author(s)

Stephen P. Miller

Director of Genetic Research
Angus Genetics Inc.
St. Joseph, Missouri, United States
LB

Luiz F. Brito

Assistant Professor
Department of Animal Sciences, Purdue University
West Lafayette, Indiana, United States
Flavio S. Schenkel, BSc., MSc., PhD.

CGIL Director, Professor
Centre for Genetic Improvement of Livestock, University of Guelph, Guelph, ON, Canada
Guelph, Ontario, Canada

The goals of this study were to develop a genetic evaluation system for a novel trait called functional heifer longevity (FHL), and determine if this novel trait is heritable. The FHL trait was defined as binary, in which the heifers received the code 1 if they had calved by the end of their third year (n = 377,938), or 0 if they were culled/sold during this period (n = 368,308). Analysis were performed using linear animal models and Bayesian inference. The significant systematic effects included in the statistical models are born by embryo transfer, year-season of birth, and age at calving (in months). Three models, differing according to their random effects (i.e., reduced model, which included only herd-year-season and additive genetic random effects; maternal genetic model, which added maternal genetic effects; and complete model, which further added maternal permanent environmental effects), were compared based on the deviance information criterion (DIC) and the estimates of genetic parameters. The reduced model was preferred according to the DIC values. However, high maternal heritabilities were estimated using the maternal genetic (0.51) and complete (0.36) models, indicating that maternal effects can impact the selection of heifers for breeding. Similar additive genetic heritabilities were estimated among the three models (0.24, 0.27, and 0.25 using the reduced, maternal genetic, and complete models, respectively), and no significant re-ranking of selection candidates were observed based on their additive genetic breeding values. Total heritabilities and correlations estimated between additive genetic and maternal genetic effects were 0.37 and -0.28 for the maternal genetic, and 0.31 and -0.27 for the complete model, respectively. This study shows that FHL is heritable, and that including maternal effects in the statistical models might be important. These results contribute to a larger project studying the genetics of female longevity in Angus cattle.