Table 1. The P-values for the effect of time on the relative change of each color indicator (ΔE, L^∗, a^∗, b^∗).

The ΔE, L^∗, a^∗, b^∗ value of eggshell during the incubation period (0–21d).

	Incubation period (day)
	0	4	8	12	16	21	P
ΔE	24.9 ± 1.0	26.7 ± 1.2	25.2 ± 1.0	24.8 ± 1.1	25.5 ± 1.2	27.9 ± 1.1	>0.05
L∗	76.3 ± 0.8	76.3 ± 1.1	77.4 ± 0.8	77.6 ± 0.9	77.5 ± 0.9	75.0 ± 0.9	>0.05
a∗	6.8 ± 0.3	6.8 ± 0.6	6.4 ± 0.4	6.3 ± 0.5	6.1 ± 0.5	6.2 ± 0.4	>0.05
b∗	18.9 ± 0.6a	21.7 ± 0.6b	20.6 ± 0.6a,b	21.1 ± 0.7 b	21.1 ± 0.7b	22.9 ± 1.0b	<0.01

Notes.

Values are the mean ± SEM, n = 30.

^{a, b, c, d}means within a row followed by different superscripts are significantly different (P < 0.05).