Table 8.

Effect of Ca source on standardized ileal digestibility (SID) of Ca and P and digestible Ca and P in the presence and absence of phytase (mean ± SE).

TRT	n	Phytase U/kg	Ca		SID, %2		Digestible, %3
			Source	GMD1, μm	Ca	P	Ca	P
1	7	0	--	--	10.06 ± 1.041e	72.18 ± 1.093b	0.003 ± 0.0081d	0.227 ± 0.0044c
3	8	0	LM	151	33.56 ± 0.974c	14.08 ± 1.022f	0.261 ± 0.0068c	0.044 ± 0.0042e
4	7	0	Bone	151	68.68 ± 1.041a	50.50 ± 1.093e	0.544 ± 0.0081a	0.277 ± 0.0044b
6	7	1,000	--	--	17.54 ± 1.041d	91.13 ± 1.093a	0.005 ± 0.0081d	0.287 ± 0.0044b
8	7	1,000	LM	151	42.62 ± 1.041b	60.84 ± 1.093d	0.331 ± 0.0081b	0.191 ± 0.0044d
9	7	1,000	Bone	151	70.42 ± 1.041a	67.07 ± 1.093c	0.558 ± 0.0081a	0.368 ± 0.0044a
P-values
Ca source					0.0026	<0.001	<0.001	<0.001
Phytase					<0.001	<0.001	<0.001	<0.001
Ca source × phytase					0.004	<0.001	0.005	<0.001

^a-dMeans within a column with different superscript letters differ (P < 0.05) based on Tukey HDS means separation. Main effects are shown and compared only when the interaction was not significant.

¹LM, limestone; GMD, geometric mean diameter. Limestone is the same limestone source with different particle sizes. Ca source was added to provide 0.7% Ca in the final diet.

²Standardized ileal Ca or P digestibilities. The non-diet related endogenous Ca and P losses was determined with 6 pens in this experiment and used for determining standardized from apparent digestibilities and were 105.6 and 190.8 mg per kg DM intake, respectively.

³Digestible Ca and P determined by multiplying analyzed Ca or P in the diets by the digestibility of that nutrient.