TABLE 2.

Effect of rearing systems on eggshell quality of laying hens (55–95 weeks of age) ^a .

Item	Egg size			Eggshell quality
	Length (mm)	Width (mm)	Shape index (mm/mm)	Breaking strength (N)	Thickness (*0.01 mm)	Weight (g)	Weight ratio (%)	Stiffness (N/mm)	Elastic modulus (N/mm2)	Fracture toughness (N/mm3/2)
System
CCS	5.84a	4.30a	1.36	34.95b	43.42	5.60	9.16	66.74b	4,689.23	305.05b
AVS	5.79b	4.28b	1.35	36.57a	43.84	5.54	9.24	67.66a	4,643.77	316.65a
SEM	0.10	0.04	0.02	0.39	0.21	0.02	0.04	0.56	29.41	2.42
Age, wk
55	5.69	4.29	1.33	37.57	44.30	5.62	9.49	72.83	4,898.44	317.54
65	5.75	4.28	1.34	38.61	45.28	5.67	9.47	70.98	4,566.53	317.52
75	5.87	4.29	1.37	35.20	43.64	5.54	9.07	65.67	4,552.50	306.25
85	5.85	4.28	1.37	35.23	43.09	5.53	9.10	64.10	4,571.99	313.60
95	5.91	4.31	1.37	32.17	41.82	5.50	8.86	62.42	4,743.05	299.33
SEM	0.10	0.04	0.02	0.39	0.21	0.02	0.04	0.56	29.41	2.42
p-value
System	<0.001	0.028	0.424	0.002	0.145	0.150	0.166	0.029	0.337	0.011
Age
Linear	<0.001	0.347	<0.001	<0.001	<0.001	0.007	<0.001	<0.001	0.144	0.017
Quadratic	<0.001	0.293	<0.001	<0.001	<0.001	0.027	<0.001	<0.001	<0.001	0.053
System × Age	0.785	0.319	0.476	0.477	0.270	0.871	0.430	0.796	0.089	0.385

^aData represent means with standard error mean. There were six replicates per age in each group. CCS, conventional caging system; AVS, aviary system.

^a,b Values within a column with no common superscripts differ significantly (p < 0.05).