Pros: smells great, horses love the taste
The first time I saw this product, it was in a feed room at a stable I was boarding my horse at. They had lots of other farm animals around, so I assumed it was for a show calf or something. But it actually was fed to a horse by one of the other boarders. I thought she was doing something weird feeding a "cow" product to a horse, so I checked into it to see "what was up".
Apparently this product has been around since the 1930s, so the fact that it is still around says something (it must work). People that have cattle, horses, pigs, goats, chickens and even rabbits feed this. It is a pelleted supplement (they are small pellets) that is 25% protein. It also has yeast for helping the digestion process, and linseed meal for conditioning the animal's coat.
I haven't met a horse that wouldn't eat this, and apparently it is often used as a top dressing when animals are stressed or sick or first learning how to eat solid food (weanlings). It smells like licorice, and apparently animals like that. I've used it when I've had to give liquid supplements and it wasn't feeding time--just take a handful of Calf Manna, pour on the liquid supplement you need to feed, and let the animal eat out of the bucket so they get all of their supplement.
Calf Manna comes in small bags (10 pounds), medium bags (25 pounds) and feed sacks (50 pounds). It keeps well in a trash can with a lid, and the smallest bags have a ziploc-type seal at the top. I've never had a mold problem, even though I fed a handful at a time to one horse (took a couple of months to get through the feed sack-sized bag).
The main ingredients are soybean meal and corn. I notice Calf Manna now when I go to places like the fair, where show cattle stay for a few days. These bags are everywhere. I have met quite a few horse people who feed this as a supplement, or even as the only concentrate their horses get. Some show people swear by it for healthy coats.
I don't use it often, but when I need a horse to eat something it may not like (liquid supplement) it comes in handy. No matter what it was mixed with, horses ate it. I guess it is the "spoonful of sugar" that helps the medicine go down.
You can find Calf Manna at farm and ranch supply stores and feed stores, in the feed section.