Table 5. Changes in eggshell thickness of eggs laid from laying hens fed vitamin D enriched diets¹

Farms	Normal diet (IU/kg feed)	Enriched diet (IU/kg feed)	Eggshell thickness (mm)				P-value
			Before		After
			Mean	S.D.	Mean	S.D.
A	4,000 IU	16,500 IU	0.39	0.03	0.43	0.02	<0.001
B	4,000 IU	16,500 IU	0.36	0.02	0.43	0.03	<0.001
C	4,000 IU	29,000 IU	0.39	0.04	0.41	0.03	0.004
D	4,000 IU	29,900 IU	0.36	0.03	0.39	0.03	0.034

Value are least squares means.
S.D.: standard deviation.