Heifers were grouped by BW (i.e.,
4 heifers per group)
and there was a 2-wk interval between
the starting date for group 1 and group 2 because
only 4 respiration chambers were available for enteric
methane measurements.Each period consisted of 14
d for adaptation and 14 d for measurements. Between
periods, a washout period was provided for 7 d during
which the control diet was fed.