Table 2 The comparison of fermentation incubation indexes. Significant differences between the means were determined by Tukey’s test. Differences were considered significant at P < 0.05

pH

7.57 ± 0.08

7.49 ± 0.03

7.61 ± 0.10

7.59 ± 0.02

7.55 ± 0.05

7.48 ± 0.05

S²⁻, μg/g

15.06 ± 0.94^a

14.83 ± 1.12^a

12.50 ± 0.50^b

12.32 ± 0.98^b

12.99 ± 1.59^ab

9.84 ± 1.44^c

SO₄²⁻, mg/g

256.94 ± 29.93

268.52 ± 61.26

221.30 ± 79.04

257.87 ± 85.95

287.96 ± 46.39

243.98 ± 70.84

Acetate, mmol/L

31.53 ± 4.01

30.19 ± 0.96

32.81 ± 3.25

32.45 ± 1.85

34.63 ± 2.23

34.15 ± 2.70

Propionate, mmol/L

15.51 ± 1.54

15.34 ± 3.40

15.21 ± 1.35

16.00 ± 1.00

16.58 ± 0.91

15.59 ± 0.74

Butyrate, mmol/L

8.33 ± 0.54^c

8.16 ± 0.56^c

9.10 ± 0.73^bc

10.81 ± 1.44^a

10.67 ± 1.22^a

10.17 ± 0.60^ab

Total VFAs, mmol/L

55.37 ± 6.00

53.69 ± 3.18

57.11 ± 5.29

59.26 ± 2.94

61.88 ± 1.98

59.91 ± 3.70

Methionine, μg/mL

246.21 ± 18.83^c

245.88 ± 15.01^c

280.39 ± 5.78^ab

257.70 ± 19.30

258.92 ± 12.08

299.12 ± 3.68^a