Table 3.

Particle size separation, estimated physically effective neutral detergent fiber (peNDF), and particle sorting of diets containing different roughage levels (wheat hay; 30% [R30] or 60% [R60]; DM basis) and supplemental fat (yellow grease; 0 (−FAT) or 3.5% [+FAT]; DM basis)

Item	Wheat hay1	R30		R60		SEM2	P-value
		−Fat	+Fat	−Fat	+Fat		Roughage	Fat	Roughage × Fat
Pens (steers)	-	6 (18)	6 (18)	6 (18)	6 (18)	-	-	-	-
NDF, % DM	58.8	27.4	27.0	41.8	41.4	-	-	-	-
Diet offered	Retained/sieve (%)
Particle size, % DM
19 mm	41.1	7.66	11.1	6.60	6.02	3.00	0.33	0.65	0.52
8 mm	9.33	25.6b	21.4b	26.5b	35.3a	3.12	0.04	0.48	0.06
4 mm	21.4	23.2ab	26.4a	24.0a	20.5b	1.04	0.03	0.90	<0.01
1.18 mm	16.8	24.1b	26.2a	24.1b	22.3c	0.654	0.01	0.86	0.01
<1.18 mm	11.4	19.4	15.0	18.9	16.0	0.935	0.84	0.02	0.45
peNDF3, % DM	42.2	15.5c	15.9c	23.9b	25.6a	0.37	<0.001	0.01	0.10
Refusal, % of diet offered	-	5.82	5.32	5.17	4.54	0.562	0.16	0.26	0.89
Sorting
Sieve size, mm
19 mm	-	0.96	0.95	0.98	0.96	0.058	0.80	0.86	0.90
8 mm	-	1.01	0.98	1.10	0.93	0.047	0.96	0.08	0.27
4 mm	-	1.00	0.94	1.06	1.12	0.056	0.03	0.96	0.29
1.18 mm	-	0.90	0.98	0.95	1.07	0.053	0.17	0.07	0.67
<1.18 mm	-	0.85	0.96	0.82	1.00	0.054	0.81	<0.01	0.47

¹ Descriptive data (n = 4).

² Standard error of the mean.

³ peNDF was calculated by multiplying the percentage of particles ≤4 mm (top three sieves) by the percentage of Neutral Detergent Fiber (NDF) of the ingredient/sample prior to separation.

^a,b,c Means without a common superscript differ (Tukey test; P < 0.05).