Table 6.

Apparent ileal digestibility of CP and AA in corn, wheat, and wheat middlings calculated using the direct or the difference procedure¹

Item, %	Direct procedure			Difference procedure			Pooled SEM	P-value
	Corn	Wheat	Wheat middlings	Corn	Wheat	Wheat middlings		Ingredient	Procedure	Ingredient × procedure
CP	73.9ab	68.6bc	45.1d	79.6a	71.8abc	63.3c	2.94	<0.001	0.001	0.034
Indispensable AA
Arg	85.1	75.1	74.8	86.5	78.2	76.0	2.21	<0.001	0.159	0.896
His	85.4	76.8	71.3	85.8	78.6	74.2	2.11	<0.001	0.191	0.815
Ile	83.6	76.0	62.5	85.4	75.8	69.8	2.87	<0.001	0.085	0.420
Leu	88.0	78.3	66.7	89.9	78.3	72.1	2.45	<0.001	0.152	0.538
Lys	75.6	62.3	53.6	79.1	63.6	63.7	3.65	<0.001	0.096	0.432
Met	88.9	81.1	69.9	92.8	81.3	76.4	2.15	<0.001	0.023	0.263
Phe	85.2	79.9	67.2	88.2	80.5	72.7	2.45	<0.001	0.164	0.611
Thr	72.0	64.1	46.0	79.1	65.9	61.6	3.47	<0.001	0.005	0.151
Trp	65.6abc	74.4a	63.2bc	58.7c	72.5ab	43.4d	3.56	<0.001	0.003	0.045
Val	78.7	71.5	58.4	83.2	72.1	67.6	2.71	<0.001	0.022	0.286
Dispensable AA
Ala	84.5	64.6	52.8	87.7	67.6	65.8	2.62	<0.001	0.005	0.104
Asp	80.9	66.5	60.6	80.5	65.3	64.2	3.87	<0.001	0.761	0.739
Cys	79.4	78.9	66.8	80.6	75.7	69.4	2.45	<0.001	0.587	0.486
Glu	88.6	89.7	78.9	84.9	88.9	78.9	2.35	0.001	0.615	0.702
Gly	61.8	60.4	37.3	64.0	68.3	59.2	4.87	0.003	0.012	0.122
Pro	80.9	87.0	59.9	99.8	100.5	91.7	5.45	0.001	<0.001	0.147
Ser	80.6	76.6	60.7	82.8	76.5	66.5	2.80	<0.001	0.178	0.556

^a–dMeans within a column lacking a common superscript letter are different (P < 0.05).

¹Data are least-squares means of 7 or 8 observations per treatment.