I went to Fleet Farm to buy a ton of 28% protein tubs. They were short so I took two 20% tubs. I winter graze and the manure indicated a little more protein may be needed. The cows went for the 20% tubs and they are gone but the 28% tubs are hardly touched. Visibly they look the same and the tag shows only difference is that the 28% tubs have "plant Protein products". Any idea?