Table 2.

Effect of AFEX wheat straw and a recombinant fibrolytic enzyme on ruminal fermentation parameters, protozoa counts, and rumen pH of wethers (n = 8 per treatment)

	Control		AFEX1			P-value
Item	Enz− 2	Enz+ 3	Enz−	Enz+	SEM	Diet	Enz4	Diet × Enz
24 h after feeding
Protozoa, × 105 per mL	6.6	5.2	18.1	8.1	0.37	0.01	0.03	0.53
pH	6.78ab	6.64b	6.70ab	6.85a	0.104	0.31	0.87	0.03
NH3-N, mM	14.2	15.7	11.4	12.6	1.25	0.004	0.16	0.83
Total VFA, mM	66.0bc	88.2a	71.3b	54.1c	7.00	0.002	0.59	<0.001
VFA proportions, mol/100 mol
Acetate	59.9	58.0	63.7	60.6	2.37	0.006	0.03	0.62
Propionate	22.3	21.5	20.7	20.6	1.24	0.03	0.44	0.51
Butyrate	11.0	11.5	10.5	11.2	1.10	0.350	0.21	0.88
Valerate	1.89	1.96	1.16	1.32	0.151	<0.001	0.15	0.54
Isobutyrate	1.85	1.67	1.26	1.54	0.179	0.010	0.69	0.10
Isovalerate	2.25	2.00	1.46	1.85	0.257	0.016	0.70	0.10
Caproate	0.47	0.41	0.35	0.36	0.144	0.02	0.56	0.35
Acetate:propionate	2.74	2.75	3.18	3.11	0.263	0.001	0.80	0.73
6 h after feeding
Protozoa, × 105 per mL	3.1	0.9	8.7	3.6	0.21	0.04	0.05	0.70
pH	5.30	5.44	5.44	5.40	0.100	0.43	0.46	0.13
NH3-N, mM	12.8	11.5	16.3	15.1	2.14	0.02	0.38	0.95
Total VFA, mM	169.3	154.7	136.5	135.9	11.33	<0.001	0.18	0.19
VFA proportions, mol/100 mol
Acetate	54.7	58.0	59.4	59.0	2.73	0.02	0.22	0.11
Propionate	26.1	23.1	26.3	25.0	1.60	0.30	0.03	0.42
Butyrate	12.6b	15.6a	11.1b	10.4b	0.96	<0.001	0.15	0.02
Valerate	1.79	1.69	1.30	1.32	0.160	<0.001	0.56	0.43
Isobutyrate	0.38b	0.57a	0.31b	0.30b	0.047	<0.001	0.01	0.007
Isovalerate	0.27b	0.46a	0.23b	0.17b	0.051	<0.001	0.07	0.002
Caproate	0.48	0.36	0.25	0.25	0.111	<0.001	0.14	0.14
Acetate:propionate	2.06	2.49	2.36	2.44	0.256	0.34	0.06	0.20

^a–cWithin a row, means without a common superscript differ (P < 0.05).

¹AFEX = ammonia fiber expansion treatment (30% AFEX straw pellets on a dietary DM basis replacing alfalfa hay pellets).

²Enz− = diet without enzyme.

³Enz+ = diet with enzyme.

⁴Enz = recombinant fibrolytic enzyme treatment effect (XYL10C, a β-1,4-xylanase, EC 3.2.1.8, GH10 from Aspergillus niger).