To compare giraffes to domestic cattle as well as
‘moose-type’ ruminants to ‘cattle-type’ ruminants in general,
species (giraffe or cattle) or digestive tract type
(‘moose-’ or ‘cattle-type’) was added as an explanatory
variable to the allometric regression model described
above, that is : ln (Y) = a + b 9 ln(BM) + c 9 (species
or digestive tract type).