In the statistical models,
interaction terms were represented by combinations of
the letters used to represent variables. In all analyses,
cows were treated as random variables.
Data on ruminal fermentation measurements were
analyzed as repeated measurements across time using
the MIXED procedure (SAS Institute, 2008) with a
model that included the effects of cow, periods, treatments,
treatment interactions, sampling time, and time
× treatment interactions. Significance was declared at
P < 0.05 and tendencies at 0.05 < P < 0.10.