Unless you're using them as a way to lure livestock away from one place and to another one or to get them corralled up, they are a waste of money in most cases. For 4 years I was scooping up fresh poop, freezing it and sending it to Texas A&M. There they would analyze it and could tell the nutritional content of what the animal was eating by what was coming out the back. There was only one time where the protein levels were insufficient and that was on a severly overgrazed pasture during a drought that had more thorn trees than grass. Otherwise, out of hundreds of samples, in all cases forage quantity was the limiting factor to animal performance, not the forage quality. Keep in mind these were pasture settings, not dry lot with animals eating hay and concentrates and included cattle, sheep, goats and horses of all ages and stages of pregnancy. Manure testing is more accurate and forage testing because the former considers what the animal is actually consuming, not what you put out in front of them. It's no different that with me, just because McDonalds has healthy salads on their menu doesn't mean I'm eating that green crud.
In most cases, putting out protein tubs probably does more for the mental satisfaction of the livestock manager than for the nutritional satisfaction of the animal. I'm sure there are plenty of people who will swear I don't know what I'm talking about, but I'm going by facts and lab results. And any used car salesman can vouch for the fact that I'm not one easily beguiled or taken in by wild claims. They don't call Missouri the Show-Me state for nothing.
