Table 1 Rumen volatile fatty acids from lactating Holstein, Jersey, Holstein-Jersey crossbreed dairy cows at 3, 93, 183, and 273 days in milk

3

93

183

273

SE

Acetate

65.30 c

66.71 b

67.75 ab

68.53 a

0.51

Propionate

18.55 a

18.01 a

16.07 b

14.71 c

0.41

Butyrate

9.98 ab

9.52 b

10.22 a

10.01 ab

0.27

Isobutyrate

0.83 b

0.86 b

0.87 b

1.06 a

0.03

Valerate

0.93 ab

0.99 a

1.01 a

0.82 b

0.04

Isovalerate

0.84 a

0.72 a

0.70 a

0.76 a

0.05

Lactate

3.44 b

3.29 b

3.38 b

4.12 a

0.15

A:P^b ratio

3.59 c

3.80 c

4.26 b

4.69 a

0.12

Total VFA^c (mM)

144.5 a

112.8 b

118.7 b

105.2 b

6.41