Most of the time when you ask someone how much they feed their horse, they answer in terms of quarts — or coffee cans. It’s an easy way to measure when scooping it out of a bin, but unless you take feed density into account, it’s a highly variable strategy. You will always end up using a volume measurement (it’s easy) but you also need to understand what that volume contains. After all the reason for feeding grain is to 1) ensure your horse’s nutritional requirements are covered and 2) add additional calories if forage isn’t enough.
Years ago I had a thoroughbred mare who always looked a bit too thin to my eye. Finally I brought in a nutritionist to evaluate my regime and explained that I was feeding her six quarts/day of Vintage Victory. What, I asked, should I add to her diet to keep her round and shiny.
I give the guy credit for not rolling his eyes. “Feed her more of it,” was his answer. He went on to explain that while this was a good feed, it was low density. A coffee can/quart weighted less than a pound (0.95). A pound of it contained 1550 calories. In comparison, the Purina Strategy I fed my other horse, weighted 1.25 lbs per quart. and although it contained a similar number of calories per pound, I was feeding my mare fewer calories by serving up the same volume. I thought I was feeding my horse plenty of food but in fact, I was short changing her.
Yesterday I was talking to a friend about her horse, who looked a bit skinny. Now, he was skinny when she bought him, but going into a New England winter, he still looked like he needed groceries. She told me the barn was feeding him six quarts/day of Sentinel LS. Now, this is a very good feed but has the same issue as the Vintage Victory. A quart of it weighs only .85 lbs and contains 1635 calories. That means that six quarts of feed is 5.1 lbs and 8, 338.5 calories.
In comparison, she had been feeding her other horse six quarts/day of Purina Ultium. A quart of Ultium weighs 1.3 lbs and contains 1900 calories. Six quarts is 7.8 pounds and contains 14,820 calories. Quite a difference!
While she thought the first horse was getting plenty of feed, there’s actually a difference of almost 6,500 calories/day from what she’s feeding the second horse.
For many horses, six quarts of Sentinel LS or Vintage Victory would be enough — the 5.1 lbs is at the low range of the recommended feeding level for nutritional content, so if a horse can hold its weight on that amount, it’s fine. Zelda, for example, is an air fern. She gets 2 quarts/day of Triple Crown Lite (1.42 lbs/quart and 1,150 calories/pound) and 1 quart of Enrich 32 (1.25 lbs/quart and 1,500 calories/lb). That’s a grand total of 5,410 calories in grain but since she doesn’t need the calories, it’s an efficient way to meet her nutritional needs (she gets free choice grass hay).
Thoroughbreds often need more calories to keep their ribs covered but at the same time, you don’t want to fill them with rocket fuel. Freedom currently gets 6 quarts/day of Triple Crown Senior (1.08 lbs/quart and 1,546 calories/pound) for 10, 018 calories of grain. In addition to that he gets 2 quarts of Alfalfa pellets (1,940 calories) and 1.5 cups of cocosoya oil (2,910 calories). So before he starts eating his free choice hay, he’s getting 14,868. While that’s almost exactly the same number of calories as feeding 6 quarts of Ultium, he does better with a lower starch feed.
You can read about the non-structural carbohydrate (NSC) content of feeds and see more comparisons of feed density and calories in this post: Calories, densities and NSC content: understanding different feeds.
Most of the time you can find the weight of a feed per quart and the calories per pound on line. If they are not posted, you can weigh a baggie containing a quart of feed on a food or postal scale, or email the feed company. Remember that not all horses need the same number of calories and that not all calories are created equal. Some horses do not do well on feeds that are high in starch/sugar and some horses do better on more densely caloric feeds (they don’t eat large volumes or they need a lot of calories/day).