There are probably more hay varieties out there in this vast world that I have never even heard of. The types of hay that I am familiar with are:
Timothy hay: This is a hearty basic hay that can be fed to horses in a considerable amount without worrying about causing a horse to gain too much weight too quickly. It consists of thick grassy stems with small one or two inch brush like tops. If you are new into the horse world, this is probably a good hay to start with.
Clover hay: Clover is considered a sweet hay that is quite rich. This hay is short stemmed with usually red or purple bulb like tops. It usually is mixed with other types of hay. If you were to buy straight clover be aware that it is not a green type of hay. It will have a tendency to turn more towards a darker brown color. The color may be off putting but as soon as you give it to your horse and see how quickly he or she gobbles it up, you will change your mind.
Orchard Grass hay: This hay is a bit richer than timothy but usually will have a blue green color. The strands of hay are usually quite long. This also is usually mixed with other hays. For some reason, horses seem to tire of just orchard grass very quickly
Coastal Bermuda hay: This is a long grassy type of hay. It is mostly grown in the southern states in a more sandy soil. It also is a hay that you can supply a large amount to your horse without worrying about too much weight gain. It is usually fed in very large round bales mostly in the winter months in order to keep something in the field for your horse to forage on. Coastal hay is notorious for colic (see Knowing the Signs of Horse Illnesses, and What Steps to Take.). Many horses do well on this hay but a very hungry horse may need to be introduced very slowly to this particular hay or a horse that does not drink a lot of water may not be the best candidate for coastal hay.
Alfalfa hay: This is the creme de la creme of hay. grown mostly in the northern, central and northwestern states, this is a deliciously rich hay for horses that has a very high protein content as well as being high in Selenium and many other nutrients, which is why lactating mares and milking cows are usually fed this exclusively. Because of its richness, it usually is paired with other hays. If you need to put weight on a horse in a short amount of time, then this is the hay to feed. However, some horses will not be able to eat just alfalfa as it will cause their stool to become too loose.
During the summer months when there is plenty of grass, you would only need hay if your horse is in the stall for more than a short amount of time. Of course, you would need hay in the summer if your horse is in a small paddock that has no grass. As far as I am concerned, alfalfa hay was produced basically as a replacement for grass during the winter months. If your horse is out in the cold weather with just a lean-to for shelter, then using a good amount of alfalfa is usually a good thing in combination with grain. Horses burn a lot of calories in the process of keeping their bodies warm in the bitter cold weather. The problem with alfalfa is it is more expensive than the average timothy or coastal Bermuda. When you feed the proper amount of alfalfa, it will be consumed in a few hours and your horse has nothing else to eat for the rest of the day. So, mixing up the hay, maybe a few alfalfa flakes and a few timothy flakes will help with the boredom issue. If you are fortunate enough to be in an area where different hays are plentiful, then try for a good mixed hay. I love the mix of alfalfa, timothy, clover and orchard grass. The horses seem to like it very much also.
Always, always check your hay. What I mean is if you see any dust coming from your hay as you move it, smell it to make sure that it is not moldy. You are always going to get a bad bale here and there or somewhere inside of a bale you will have a few bad flakes. Moldy hay can colic your horse in a matter of minutes not to mention that respiratory problems can arise if you consistently feed your horse hay that is moldy or musty. If you give your horse hay and when you come back to feed, there is a lot of waste, cut back a flake. The next day, same thing, cut back another flake until you find the right amount for each horse. Making your horse clean up all of the hay in the stall is a good thing. Horses were born to foriage. If you have a horse that hogs up the hay very quickly, you may have to go to a lighter hay that you can feed more of, that way, he or she will not be standing hours on end with nothing to eat. Boredom can sometimes cause horses to start weaving, stall walking, cribbing or chewing down the barn.
Learning about the different types of hay, which type is best for which horse and how much to give takes time to learn. Like anything else in life, it is about balance. The balance between the right amount of feed, the right amount and right kind of hay, and the right amount of exercise are all lessons learned. Pay attention to your horses weight. Don’t be afraid to ask questions. Trial and error will help you understand their nutritional as well as emotional needs. If you see changes in your horse that you do not like or something that they do not like, make adjustments. Rely on your instincts and how you feel. If it doesn’t feel right, it probably isn’t. As long as all changes are subtle, it’ll be jusssssst fine.