Table 2. Reference gene stability value ranked by geNorm and BestKeeper algorithm in liver and spleen of laying hens of the 80 weeks of production.

Tissue	geNorm									BestKeeper
	CC			CF			CC-CF			CC			CF			CC-CF
	Ranking		M value	Ranking		M value	Ranking		M value	Ranking		Standard Deviation	Ranking		Standard Deviation	Ranking		Standard Deviation
Liver	1	ACTB	0.89	1	ACTB	0.60	1	ACTB	0.78	1	GAPDH	0.19	1	GAPDH	0.11	1	GAPDH	0.17
	2	HMBS	0.92	2	GAPDH	0.65	2	GAPDH	0.85	2	ACTB	0.20	2	RNA18S	0.16	2	ACTB	0.20
	3	GAPDH	0.94	3	HMBS	0.79	3	HMBS	0.88	3	HMBS	0.24	3	ACTB	0.17	3	RNA18S	0.21
	4	RNA18S	1.73	4	RNA18S	0.79	4	RNA18S	1.36	4	RNA18S	0.27	4	HMBS	0.20	4	HMBS	0.23
Spleen	1	GAPDH	0.35	1	HMBS	0.43	1	ACTB	0.46	1	HMBS	0.33	1	RNA18S	0.14	1	HMBS	0.28
	2	ACTB	0.37	2	ACTB	0.45	2	GAPDH	0.46	2	GAPDH	0.36	2	ACTB	0.22	2	RNA18S	0.31
	3	HMBS	0.43	3	GAPDH	0.46	3	HMBS	0.52	3	ACTB	0.36	3	HMBS	0.24	3	GAPDH	0.31
	4	RNA18S	0.69	4	RNA18S	0.93	4	RNA18S	0.94	4	RNA18S	0.38	4	GAPDH	0.25	4	ACTB	0.32

CC: conventional cage; CF: cage-free; CC-CF: overall data.