Good choice to get rid of the corn. My brother is an animal nutritionist, and as he put it - corn is good ONLY for feeder pigs and feeder cattle. In other words, animals intended to be fattened up for slaughter. My horses are on VERY clean grass (bermuda which is really all that grows here) hay, that was cut young so that it is soft, pallatable, and highly digestable. And very little grain. Right now they are on about 1 pound crimped oats each a day, that's it. But they were all in excellent "bloom" to begin with, wormed regularly, and get regular dental work. And they are all quite 'fluffy' (meaning fat).