In the present study, which involved a wider range of
concentrate levels, a larger number of cows, and 4 measurement
periods, daily CH4 emissions ranged from 272
to 287 g/d, and in common with the findings of Young
and Ferris (2011), were unaffected by concentrate
supplementation. However, as ample evidence exists
that DMI is a key driver of CH4 emissions from animals
offered confined diets (Ellis et al., 2007), concentrate
feeding, which normally results in an increase in total
DMI (as observed in the current study) might have
been expected to increase daily CH4 emissions. That
this did not occur is likely to reflect the decreasing forage
proportion in the diet as concentrate feed level increased.