Table 3 Effect of slow-release urea supplementation on fermentation pH and characteristics in Rusitec

pH

6.81

6.80

6.80

6.77

0.01

0.25

0.47

0.03

NH₃-N, mmol/L

7.70

9.31

10.25

8.92

0.37

0.01

0.39

0.03

Total VFA, mmol/L

78.5

80.2

79.3

85.7

2.86

0.21

0.65

0.08

 Acetate (A)

46.1

45.6

46.4

47.2

0.57

0.57

0.16

0.16

 Propionate (P)

26.9

25.7

26.0

26.5

0.21

0.01

0.01

0.16

 Butyrate

14.9

15.5

15.2

14.2

0.24

0.38

0.13

0.04

 BCVFA³

2.8

3.2

2.9

3.2

0.09

0.87

0.01

0.02

 Valerate

7.8

8.4

7.9

7.4

0.25

0.63

0.03

0.22

 Caproate

1.3

1.6

1.5

1.4

0.05

0.02

0.01

0.08

 A:P

1.69

1.77

1.78

1.77

0.03

0.01

0.24

0.02

Total VFA, mmol/d

50.5

53.1

52.0

55.9

2.05

0.13

0.18

0.06

Protozoa, × 10⁴/mL

2.4

2.9

2.8

2.8

0.24

0.91

0.17

0.24