FREE-FEEDING FOR WINTER

By Heidi Smith, DVM

With the onset of winter, one of the biggest concerns in keeping horses healthy is ensuring that they can generate sufficient body heat to stay warm during cold weather. Obviously, it takes more calories to stay warm in the cold, but what is the best way to provide those calories? The following is a brief review of how equine digestion works and a simple solution that has worked well for us.


Although the horse is a monogastric (one stomach), his digestive tract differs a lot from that of a dog or a human. His stomach is quite small relative to his body size (only about twice the size of a human's stomach) and the remainder of his digestive tract has some unique adaptations that enable the horse to be an efficient grazing animal. The most noticeable adaptation to forage digestion is his large colon; it fills the majority of the horse's large abdominal cavity. It is here and in the adjacent cecum that a large amount of forage digestion takes place.


Bacteria in the large colon and cecum have the capability of breaking down the cellulose in forages that cannot be processed in the small intestine. When the chemical bonds that hold the cellulose together are broken, heat is released. This is a very useful byproduct in cold weather when the horse is trying to stay warm. Further processing of the cellulose by the bacteria yields compounds called volatile fatty acids. These compounds are absorbed into the bloodstream and can be utilized directly in the Krebs cycle (the metabolic process in the cells that releases energy) just as blood glucose is.
It is now understood that in horses that perform aerobic work (such as endurance horses or ranch horses), the volatile fatty acids from forage metabolism actually provide a very large percentage of the horse's energy needs. Furthermore, since the digestive process in the large colon and cecum is constant and ongoing, the energy provided by volatile fatty acids is very steady--ideal for keeping a horse warm in cold weather.


Another source of heat is protein. The chemical bonds in protein are especially strong, and release a large amount of heat when broken in the digestive process. Hence high protein feeds are very appropriate in winter weather, but a detriment in hot summer weather in horses working hard and having to get rid of excess body heat. Extra protein is further metabolized into useable energy which can be used to produce more heat.


The ideal feeds for winter, then, are forages, and particularly those with protein levels higher than maintenance levels. In other words, high quality hay is the ideal winter feed, and alfalfa becomes a good choice as the weather gets colder.
The next problem is how to best get sufficient amounts of hay into a horse to provide his heat needs. The horse's small stomach makes meal feeding less than ideal. In herd situations, dominant or greedy individuals will often eat more than their share of meal-fed hay, depriving less aggressive or slower-eating individuals of adequate feed. Furthermore, if the horse rapidly consumes his share, his digestive tract will have active periods and slow periods, as the reflex stimulation of a full stomach causes activity further down the tract. This is not conducive to a steady state of digestion in the large colon and cecum.


We've addressed this issue in our own horses for the past several years by free-feeding hay in large bales. In nature, horses graze off and on continually, taking small meals at frequent intervals. Free-feeding approximates their natural grazing habits. It has been our experience that when meal-fed horses are initially offered free-feeding, they will only overeat for about 4 or 5 days. After that, they begin to self-regulate. We've compared hay consumption between free-fed groups and meal-fed groups, and have found that after the initial week or so, we actually feed slightly less tonnage when free-feeding. Some of this can be attributed to less waste, as the feed is all in one area. But it also illustrates that the free-fed horses will regulate their feed intake once they are used to the system.


We've found with free-feeding that there is no meal-time frenzy as there is in groups being fed hay at twice or three times daily intervals. All horses can go to the big bales whenever they are hungry, and the aggressive ones do not tend to pick on the timid ones since there is no competition for feed. The best benefit, though, has been the condition of our horses. We free-feed horses ranging in age from weanlings to geriatrics, and find that they all maintain weight well. Slower-eating horses can keep up with their herd mates, older horses are not pushed out by those in the prime of life, and youngsters can also get their needs met. We currently free-feed three different social groups. We maintain a bachelor herd of young stallions, a group of dry mares, and a group of nursing mares, youngsters, and geriatrics. The latter group gets alfalfa or alfalfa-mix hay at all times to meet the protein (particularly lysine) needs of the younger horses and nursing mares. The other two groups get good grass hay (timothy or orchard grass) and only get alfalfa when the weather is fairly cold. All three groups regulate their intake well, with quantity of hay consumed going up noticeably when the weather is severe. In winter, our free-fed horses maintain weight well and come through severe cold snaps without shivering or showing adverse effects from the cold. They seem to regulate their intake relative to the weather far better than we can--when meal-feeding, it is guesswork to estimate a horse's particular needs on a cold night and adjust his feed by an extra flake or two.


After five years of free-feeding, we have also noticed better overall dental health in our horses. We attribute this to the fact that free-feeding more closely approximates natural grazing and browsing, and hence provides wear on the teeth more in keeping with their normal eruption rates.


Another added benefit has been a decrease in the labor required to feed a large number of horses. It is a simple matter to have the large bales loaded in the back of a pickup, and to drive out into the pasture and pull them off, using a tree, fence post, or second vehicle as an anchor. Compared to the usual system of having to meal-feed twice daily, making sure that flakes are sufficiently separated to prevent fighting, this has proven for us to be a much more time-efficient system.

 
Heidi Smith, DVM
PO Box 103
Tendoy, ID 83468-0103
Phone (208) 756-6060