In the present study (Table 12), specific gravity was
increased by lowering CP from 39 to 42 wk of age (P =
0.014) and from 47 to 50 wk of age (P = 0.049). Novak
et al. (2008) found no significant differences in specific
gravity at any time. In a previous report (Scheideler
et al., 2005), feeding hens a diet with lower CP (4%
points) reduced specific gravity, but did not decrease
egg production (%). This could be related to the foundation
of the shell (protein matrix; Fraser et al., 1998)
because it was suggested that limiting amino acids for
the development of this protein matrix may negatively
influence shell quality