The National Research Council (NRC) sets nutrient requirements for horses and other animals and does an excellent job estimating the correct calorie, protein and mineral intakes for ?average? horses. However, for the very large or
very small animal, you may need to make adjustments.
Feeding guidelines are based on studies typically done using horses that weigh 900 to 1,100 lbs. Does that mean you feed your 500-lb. pony half of what you feed your 1,000-lb. Thoroughbred, and then you double it for a 2,000-lb. draft' Not necessarily. The smaller or larger animal can have different metabolism, different muscling and bone mass.
Calories.It may take some experimentation, but calories is the easiest thing to get right because you can see the results. At the ideal weight, your horse's ribs are covered but easily felt. His neck blends smoothly with the shoulder, hips rounded. There are no lumpy fat deposits and no crease down the back.
While ?hot? light horse breeds may require some grain to hold a good weight, smaller equines don't, and many will become obese and insulin-resistant if fed grain.
Feeding hay as a percentage of bodyweight works best. For maintenance to light use, feed 1.5 to 2% of the bodyweight as hay (1.5 to 2 pounds of hay per 100 pounds bodyweight), with a mineral supplement to balance the hay.
The heavy breeds also can be fed this way. However, they're highly insulin-sensitive, making their metabolism efficient at fueling their muscles. When not in regular, heavy work, concentrated carbohydrate (grain) can be too much of a good thing. They also may have a higher proportion of their bodyweight as bone, a tissue with low calorie demands.
Protein. Never skimp on protein. Overfeeding it isn?t harmful (just expensive). That said, hardier pony breeds appear to have lower protein needs than their larger cousins. As a rule of thumb, if you're feeding 1.5 to 2% of bodyweight as hay, and the hay is at least 7.5% protein, you don't need to supplement protein.
Conversely, heavily muscled horses may need more protein than predicted by studies in lightly muscled horses. Providing some of their hay as alfalfa, and using a 30% protein mineral supplement is good insurance.
Minerals. Many of the pivotal mineral feeding recommendations came from research using ponies, so the NRC recommendations are reliable for ponies and small breeds. In fact, these smaller breeds may be more efficient at absorbing minerals, so full-size and large-breed horses may be getting short changed with NRC data.
Since NRC mineral recommendations are minimums, and mineral assays can have a large inherent error, full-size horses should have at least 150% of the recommended minimums. For very large breeds, 200% is a good target.
Horses are very tolerant of high mineral intakes. You have to get to at least 1000% of the minimums, sometimes higher, for any mineral to approach a toxic level in the horse.