Figure 2.

Regression coefficients (${\beta }_1$) ± standard errors of regression of total number of eggs laid from 18 to 29 weeks of age (A), total number of eggs laid from 30 to 69 weeks of age (C) and the adult body weight at 69 weeks of age (E) pertaining to the bone mineral densities (BMD) of the keel bone, and the effect of total number of eggs laid from 18 to 29 weeks of age (B), total number of eggs laid from 30 to 69 weeks of age (D), and the adult body weight at 69 weeks of age (F) on the BMD of the keel bone in four chicken layer lines (WLA, R11, BLA, L68). Significant regression coefficients are marked with asterisks (* p < 0.05, ** p < 0.01, *** p < 0.001).