Table 3 Rumen pH, volatile fatty acid (VFA) profiles and ammonia-N concentration after 6 h in vitro incubation

Rumen pH

6.17

6.17

6.18

6.19

0.014

0.971

0.641

1.000

Total VFA, mmol/L

73.8

74.8

75.9

76.5

0.391

0.056

0.009

0.738

 Acetate

63.0^a

62.8^b

62.7^b

63.1^a

0.044

0.003

0.380

<0.001

 Propionate

20.4^a

20.1^b

19.9^bc

19.7^c

0.074

0.001

<0.001

0.324

 Butyrate

12.2^c

12.7^b

13.1^a

12.9^ab

0.090

<0.001

<0.001

<0.001

 Isobutyrate

1.16^a

1.14^b

1.11^c

1.08^d

0.009

<0.001

<0.001

0.715

 Valerate

1.25^b

1.29^ab

1.30^a

1.31^a

0.008

0.015

0.002

0.457

 Isovalerate

2.07^a

2.01^b

1.95^c

1.89^d

0.018

<0.001

<0.001

0.804

A:P ratio³

3.09^c

3.12^bc

3.16^ab

3.19^a

0.012

0.002

<0.001

0.987

Ammonia, mg/dL

28.9^a

27.5^b

26.8^b

26.6^b

0.291

0.005

<0.001

0.114