How big is your mini? How tall? Barely 3# of feed daily doesn't seem like much feed, unless your mini is very small. [is that 2 cups dry or wet beet pulp?]
My smallest mini eats more than that, he's 31" tall, and weighs 175#; he gets 1.5# senior feed and 2-3# hay daily (he doesn't always eat all his hay, but usually eats most of it).