Eggshell Quality
From Table 1, we can see the eggshell
strength in G light was significantly (P < 0.01)
better than those in W and B lights. From 21
to 45 wk, eggshell strength in W, B, and G
treatments decreased by 0.9, 0.38, and 0.12 kg/
cm2, respectively, butincreasedby0.03kg/cm2
in the R light group. Correlation coefficients (r)
between eggshell strength (kg/cm2) and age
among all light treatments were highly signifi-
cant (P < 0.01) in W light only (Figure 2E).
This result was similar to the report of Pyrzak
et al. [4] for laying hens in the first laying
cycle, in which eggshell strength in G light was
significantly better than those in other groups.
Nevertheless, our result was not similar to his
report in the second laying cycle, in which
eggshell strength in B and G lights was better
than those in R light. These different results
could be due to the measurement range; Pyrzak
et al. [4] measured it in 2 laying cycles, and
we measured it within 21 to 45 wk.
Eggshell thickness in the G light group was
significantly (P < 0.05) thicker than those in