I feed a sweet feed mix to all my animals (horses, pig, goats,) so I only have one mix around. Most on here will tell you to stop the sweet feed....I use it and don't have a problem. The amount you are giving is small so I wouldn't worry about it, if it were me.
Yes, get rid of the pallets and put down a thick bed of straw. You will have to muck stalls more often, but they will definitely be warmer on the ground in a bed of straw.