Table 5.

Main effects of diet and age on in vivo shank cross-sectional area in the proximal metaphysis in hens fed different dietary aP and Ca levels, and phytase supplementation from 25–37 wk of age¹.

	Bone cross-sectional area (mm2)
	Total2		Cortical3		Trabecular + medullary4
	LSM5	SEM6	LSM5	SEM6	LSM5	SEM6
Diet7
PC	26.5c	0.21	12.5a	0.15	12.9c	0.23
NC	28.1a	0.41	12.1a,b	0.08	14.8a,b	0.46
NC + 150	26.7a,b,c	0.48	12.0a,b,c	0.12	13.6a,b,c	0.40
NC + 300	27.5a,b	0.24	11.7b,c	0.12	14.8a	0.21
NC + 600	27.3a,b,c	0.26	11.5c	0.14	14.7a	0.17
NC + 1,200	26.4b,c	0.30	11.8b,c	0.13	13.6b,c	0.21
PC + 1,200	26.2b,c	0.44	12.1a,b,c	0.14	13.1b,c	0.38
Age
25 wk	26.7	0.27	12.3a	0.11	13.3b	0.21
29 wk	26.9	0.25	11.9b	0.10	13.9a,b	0.22
33 wk	27.2	0.26	11.9b	0.09	14.2a	0.25
37 wk	27.1	0.27	11.7b	0.09	14.3a	0.26
Source of variation	Prob > F
Diet	0.003		<0.001		<0.001
Age	0.621		<0.001		0.010
Diet × age	0.999		0.999		0.999
Body weight8	<0.001		<0.001		<0.001

^a-cMeans within column with no common superscript differ significantly (P ≤ 0.05).

¹Means of 6 replicates of 1 hen for each treatment.

²Total term was the weighted average of both the cortical and trabecular + medullary bone measures.

³Cortical bone was the outer shell of the bone that was determined to have a density >500 mg/cm³.

⁴Trabecular + medullary bone were assumed to be present in the trabecular space.

⁵LSM = least squares mean.

⁶SEM = standard error of the mean.

⁷PC, a positive control diet, nutritionally complete diet containing 0.45% aP, 3.70% Ca, and 0.16% Na (25–28 wk) and 0.38% aP, 3.73% Ca, and 0.15% Na (29–37 wk); NC, a negative control diet, similar to the PC diet but having 0.22% aP, 3.00% Ca, and 0.13% Na (25–28 wk) and 0.19% aP, 3.02% Ca, and 0.13% Na (29–37 wk); NC + 150, NC + 300, NC + 600, and NC + 1,200, the NC diet supplemented with 150, 300, 600, or 1,200 FTU Quantum Blue phytase (AB Vista, Marlborough, UK)/kg, respectively; and PC + 1,200, the PC diet supplemented with 1,200 FTU Quantum Blue phytase/kg.

⁸Body weight was used as a covariate.