Table 3.

The effects of genotype, housing system, and feed Ca level and their interactions on eggshell quality parameters.

Factor	Item		Shell Weight (g)	Shell Strength (g/cm2)	Shell Thickness (mm)	Egg Shape Index (%)	Shell Index (g/100 cm2)
Effect of Individual Factors
Genotype RMSE	ISA Brown		6.1 b	4265 c	0.362 b	77.2 b	9.9 b
	Bovans Brown		6.5 a	4839 a	0.373 a	77.5 a	10.5 a
	Moravia BSL		5.8 c	4369 b	0.330 c	77.0 c	9.6 c
			0.69	848	0.18	2.80	0.74
Housing RMSE	Littered floor		6.2	4604	0.353	77.2	10.0
	Enriched cages		6.1	4654	0.363	77.3	10.0
			0.74	865	0.187	2.81	0.81
Ca RMSE	3.00		6.2 a	4673 a	0.365	77.3	10.1 a
	3.50		6.0 b	4590 b	0.352	77.2	9.9 b
			0.74	864	0.187	2.81	0.81
p-value	Genotype		***	***	**	**	***
	Housing		NS	NS	NS	NS	NS
	Ca		*	**	NS	NS	*
Analysis of Interaction between the Factors
ISA Brown	Littered floor	3.00	6.1 b	4408 cd	0.348	77.1 ab	9.8 ab
		3.50	6.3 ab	4773 ab	0.361	76.6 b	10.1 ab
	Enriched cages	3.00	5.9 bc	4723 ab	0.391	77.8 ab	9.9 ab
		3.50	5.8 bc	4638 ab	0.352	77.4 ab	9.9 ab
Bovans Brown	Littered floor	3.00	6.7 a	5089 a	0.381	78.1 a	10.7 a
		3.50	6.3 ab	4868 ab	0.368	77.9 ab	10.3 ab
	Enriched cages	3.00	6.7 a	4943 a	0.383	77.1 ab	10.7 a
		3.50	6.4 ab	4562 bc	0.363	77.3 ab	10.3 ab
Moravia BSL	Littered floor	3.00	5.8 bc	4328 cd	0.327	76.6 b	9.6 b
		3.50	5.8 bc	4236 d	0.328	77.3 ab	9.6 b
	Enriched Cages	3.00	5.6 c	4599 bc	0.331	77.5 ab	9.5 b
		3.50	5.8 bc	4384 cd	0.333	76.8 b	9.7 ab
		RMSE	0.68	835	0.186	2.79	0.73
p-value Genotype × Housing			***	***	NS	***	NS
Genotype × Ca			***	***	NS	*	***
Housing × Ca			***	***	*	NS	***
Genotype × Housing × Ca			***	***	NS	***	***

Results of the variance analysis are indicated as significant (* p ≤ 0.05, ** p ≤ 0.01, *** p ≤ 0.001) or not significant (NS). ^a,b,c,d Mean values in the same column marked with a different superscript indicate statistical significance (p ≤ 0.05). Mean values with no superscript are not significantly different from any other values. RMSE: Root Mean Square Error.