179 Expected progeny differences for stayability in Angus cattle using a random regression model

Stability of genetic predictions for stayability using random regression models that include end points beyond 6 yr of age

“…With respect to the regressions of predictions obtained with the RRM on the traditional method, an underestimation of the genetic merit for STAY06 occurred with the traditional threshold model when compared to the RRM. Similar results were reported by Sánchez-Castro et al (2017) when comparing EPD for STAY at consecutive ages. Among the seven RRM implemented in this study, all of them had essentially the same predictive power for the 6-yr EPD for STAY, since all correlations and regression coefficients obtained for these models were close to 1.…”

“…Within this context, random regression models (RRM) have been successfully applied to STAY data, since binary observations can be assigned to any discrete point in time during a cow’s lifetime and expected progeny differences (EPD) with higher accuracies can be generated for any particular age ( Jamrozik et al, 2013 ). Prior research efforts using RRM have included earlier age end points in the estimation of an aggregated 6-yr STAY genetic prediction ( Sánchez-Castro et al, 2017 ); however, predictions using regression equations have a tendency to be variable, particularly at the ends of the prediction range. For traits such as STAY, there is potential to extend the age end points beyond 6 yr of age in order to increase the stability of the 6-yr STAY EPD in comparison with the increases in accuracy associated with RRM that finalize their prediction range at the age of 6 yr.…”