Random regression models : Let [Y.sub.hijk] denote either BW or DFI at k days of age (from 64 to 230 days for boars and from 80 to 253 days for gilts) for pig j (j = 1,2, ..., 151 for boars and j = 1,2, ..., 162 for gilts) of line i (i = 1,2; 1 is LRFI and 2 is CTRL) raised in pen h (h = 1,2,...,12).
Based on the Gompertz model, LRFI boars had slightly lower mature feed intake (2.93 vs.
Selection for reduced RFI has led to a lower population curve for DFI for the LRFI than the CTRL line (Figure 4).
This hierarchical setting of RR models allows each pig within a pen to have its own regression coefficients, which are randomly deviated from their line (LRFI and CTRL) means.
In this study, we also found that differences between the LRFI and CTRL lines in estimates of coefficients from the Gompertz model for DFI and BW were not consistent between boars and gilts.