Just wandering why they feed it to the calves if it want fatten a hog up? Isn't it suppose to fatten the calves up?
The feed that they are feeding yearling calves is most likely some kind of sweet feed, ground up grain with molasses on it. This kind of feed is usually only about 8 to 12% protein. I would not call this a high protein diet. This kind of diet is usually given to the yearling calves to fatten them a little, but more than anything, grow them before they ship them to the feedlots. Sweet feed will get a hog fat and they love it because of all the molasses. As for the high protein deer feed, it is pretty unlikely that one hog could eat enough of it get that big. As everyone else said it is probably a combination of all the factors of genetics, feed, and environment that allows this hog to get so big.
