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. 2018 Jul 20;96(9):3928–3942. doi: 10.1093/jas/sky251

Table 6.

Effect of recombinant fibrolytic enzymes on pH, ammonia-N, VFA, gas, methane (CH4) and microbial N production, protozoa numbers, and enzymatic activities of a barley straw–concentrate diet in the RUSITEC

Treatments1 Contrasts P-value
Item Control EGL7A XYL10A XYL10C SEM Con vs. EGL7A Con vs. XYL10A Con vs. XYL10C
pH 6.79 6.78 6.78 6.78 0.023 0.27 0.37 0.25
Ammonia-N, mg/d 94.1 94.2 103.7 96.2 6.489 0.98 0.01 0.57
Total VFA, mmol/d 44.8 44.4 45.7 44.4 3.04 0.73 0.48 0.74
 Acetate, mol/100 mol 66.0 65.9 67.4 66.4 1.54 0.80 0.02 0.47
 Propionate, mol/100 mol 23.9 24.0 22.9 23.7 0.82 0.76 0.02 0.70
 Butyrate, mol/100 mol 6.69 6.61 6.52 6.60 0.501 0.74 0.49 0.71
 Valerate, mol/100 mol 1.57 1.55 1.48 1.58 0.122 0.86 0.38 0.93
 Isobutyrate, mol/100 mol 0.69 0.73 0.72 0.71 0.027 0.09 0.16 0.53
 Isovalerate, mol/100 mol 1.07 1.18 1.20 1.09 0.059 0.01 0.003 0.65
 Caproate, mol/100 mol 0.06 0.06 0.06 0.06 0.013 0.86 0.77 0.63
Acetate:propionate 2.77 2.78 2.96 2.78 0.158 0.90 0.01 0.87
Total gas production, L/d 1.59 1.78 1.66 1.59 0.222 0.01 0.38 0.98
CH4, % 5.2 5.2 5.1 5.3 0.70 0.97 0.68 0.94
CH4, mL/d 91.5 106.4 88.5 91.9 18.83 0.27 0.82 0.98
CH4, mg/d 59.4 70.8 57.5 59.7 11.92 0.19 0.81 0.97
CH4, mg/g incubated DM 5.7 6.8 5.5 5.7 1.02 0.08 0.73 0.99
CH4, mg/g degraded DM 11.6 14.4 11.1 11.8 2.30 0.02 0.63 0.86
Protozoa (× 104) 9.6 10.8 9.5 12.0 1.67 0.37 0.92 0.09
Production of microbial N, mg/d
 Effluent 31.3 33.5 35.1 32.0 2.92 0.14 0.01 0.65
 FPA2 4.8 4.8 5.2 4.9 0.29 0.96 0.06 0.80
 FPB3 straw 27.5 27.1 29.3 29.4 0.80 0.63 0.05 0.03
 FPB concentrate 4.8 5.2 4.5 4.5 0.32 0.23 0.47 0.53
 Total 69.5 70.8 72.4 70.2 2.30 0.32 0.03 0.59
Enzyme activity (µmol/min per gram)
 Xylanase 420.8 407.3 419.9 396.3 20.21 0.53 0.97 0.26
 Endoglucanase 6.21 10.33 9.61 5.92 1.096 0.01 0.03 0.85

1EGL7A = endo-β-1,4-glucanase, EC 3.2.1.4, GH7 from Thielavia terrestris; XYL10A = 1,4-β-xylanase, EC 3.2.1.8, GH10 from Rasamsonia emersonii; and XYL10C = 1,4-β-xylanase, EC 3.2.1.8, GH10 from Aspergillus niger.

2FPA = feed particle-associated bacterial fraction.

3FPB = feed particle-bound bacterial fraction.