A lot of people swear by sweet feeds -- its very easy to find inexpensive ones -- and a lot of people won’t ever buy them for their horses because of the negative health effects associated with them.
However, when discussing these feeds, it must be noted that they have a VERY large range of quality. There are some that are very bad for your horse, as well as some that will not do too much damage to his digestive system.
Anything that has added sugar is considered a sweet feed. This includes both textured feeds (those with particles that are visibly different) as well as pelleted feeds.
There is a common misconception that pellets can't be sweet feed, but that is just that, a misconception. Pelleted feeds can contain just as much (if not more) sugar than textured feeds.
Usually the sugar is added to feeds in the form of molasses. Molasses in and of itself is not bad. In fact, in small amounts, it can be beneficial, as it is a good source of copper.
Inexpensive (ESPECIALLY the ones that are less than $10 for a 50 pound bag) sweet feeds that are grain based are some of the worst feeds for horses.
Usually these feeds have high amounts of added molasses, at which point the negatives outweigh the positives for its addition. What’s the reason for the high amount of molasses? It is to cover up the taste of the low-quality ingredients that go into these feeds.
You get what you pay for in this world, and its also true for horse feeds. To make those bags of feed so inexpensive and still make money, the feed company must use the cheapest ingredients they can, which are usually very low quality.
In fact, a lot of times the ingredients in one bag might not even be the same as in the next bag! (Take a look at the ingredient list section of reading a feed tag for details...)
...now, back to the sugars.
Compounding the problem is the fact that these feeds are usually very high in corn and other grains...which are very high in sugar and/or starch themselves. This sugar and starch is not handled well by the digestive system of the horse. In addition to not being handled well, all the sugar and starch creates a sugar-high -- kind of like when you give a pre-schooler candy bars for lunch!
You wouldn’t give your pre-schooler a diet of soda and candy bars, so why would you do the same to your horse?
Yet that is exactly what these feeds are.
Ever heard of horses getting “hot” on grain? The sugars and starches are the culprit. Often "hot" horses can very successfully be fed alternative low-grain feeds (even low-grain sweet feeds) and remain calm and manageable.
Also, these inexpensive feeds are usually meant to be fed at rates of 6-10 pounds per day...which is a lot of feed. It is also a LOT of sugar.
Some of the higher end sweet feeds are not near as bad as the inexpensive ones. However, some of them are just as bad, if not worse. And for the price you pay for a bag of the high-end feeds, you could buy an alternative forage-based feed that would be healthier for your horse.
If you do decide to feed your horse sweet feed, make sure to look for the following to minimize the sugar/starch you are feeding him (and therefore its potential negative effects):