This article is from the Mastiffs Breed FAQ, by mmcbee@access.mountain.net (Mike McBee) with numerous contributions by others.
Probably not as much as you think. Pound for pound, the
larger the dog the less food it needs for each pound of body
weight. Exactly how much food your dog needs depends on many
factors including its size, age and activity level. Feed your
Mastiff a good quality, balanced diet - low on table scraps -
and don't let him get too fat.
 
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