Ask The Nutritionist Juliet M. Getty, Ph.D.

Q: How do I transition to free choice hay?

A: Horses instinctively know how much food they need to maintain overall body condition. But when they experience gaps in their forage supply, they become stressed, releasing hormones that ultimately promote fat storage, increase inflammation, and potentially lead to disorders including ulcers, colic, metabolic syndrome, Cushing’s disease, and laminitis. They perceive themselves as starving and go into survival mode, “inhaling” every batch of hay you provide. But amazingly, when they are allowed to have a never-ending supply, they will calm down, eat less, and self-regulate their intake.
Here are the guidelines:

• Start with a grass hay if your horse is overweight or gains weight easily. Grass hay (e.g., timothy, Bermuda, orchardgrass, brome, Teff, etc.) tends to be lower in calories than alfalfa — not because of differences in the sugar/starch content (which is surprisingly low in alfalfa), but because of its lower protein content. Alfalfa is very helpful in boosting protein quality and can be part of a nutritious forage-feeding plan. But stay away from grass/alfalfa mixes when feeding hay free-choice. Horses will pick out the tasty alfalfa and end up eating too much of this calorie-dense forage. 
• Analyze your hay. Free choice only makes sense for the easy keeper if the hay is low in calories, as well as low in sugar and starch. You can’t expect your horse to lose weight if you give him all the “candy” he wants. Sugar and starch increase the blood’s insulin level, which keeps your horse fat. The ethanol soluble carbohydrates (ESC) plus starch should be less than 10% on a dry matter basis, and the digestible energy (calories) should not be higher than 0.94 Mcals/lb on a dry matter basis.
• Don’t let your horse run out of hay, not even for ten minutes!  The key to self-regulation is for your horse to have hay available always. If he runs out, even for 10 minutes, he will never get the message that there is always forage available and he will remain in “survival mode.”  Be sure to give him enough hay to last all night long – there needs to be some left over in the morning. And then watch for when he walks away from his hay supply – that’s the magic moment that says he’s getting the message!
• Patience. At first, the horse will overeat and will seemingly never leave the hay pile. This is because he still feels that he needs to eat all he can to survive. He will develop a “hay belly” which is not fat and is quite normal – it’s caused by gas production from microbial hay fermentation within the hindgut. It is likely that he will gain a few pounds, initially. Depending on the horse’s history, self-regulating can take as little as a week, or as much as many months if the horse’s metabolism has been damaged over years of suffering with a reduced forage supply. But eventually, it does happen if you give your horse a chance for his instincts to kick in.
• Consider a slow feeder. These systems are useful in slowing down the amount of hay the horse eats and can be very helpful as long as they do not go empty. Make sure there is some left over in the morning, so you know that there was hay available all night long. Also, give your horse time to get accustomed to the new system by offering hay in the hay net or feeder, as well as loose on the ground. Your goal is to avoid frustration. 

Many horses who have been damaged over time will develop leptin resistance, which simply means that the horse’s brain does not get the signal to stop eating. To remedy this situation, in addition to forage free-choice 24/7, make sure the diet is high in anti-inflammatory nutrients, low in sugar and starch, and free of soy. 

Forage, freely available at all times, along with companionship, and room to move and roam, will help your horse live a vibrant, healthy life.