Underweight: Solutions for the Hard Keeper
By Juliet M. Getty, Ph.D.
You might be relieved to have a horse who doesn’t have an obesity problem. Carrying less weight certainly has its advantages: less strain on joints, faster metabolism, and lower risk of a laminitis.
But if your horse is underweight, where the ribs easily show, and the spine and hip bones are not covered with enough tissue, there could be a problem. If you’ve tried to put weight on your horse without success, there is reason for concern. But the solution may be easier than you think.
First, rule out three things:
1) Dental problems -- The most common reason for weight loss is poor teeth. Watch your horse while eating – does he drop a lot of food; does he spit out clumps of partially chewed grass or hay? His teeth or gums may need attention. If your horse is getting up in years, tooth loss may be issue.
2) Worms – Test your horse’s manure every three months and work with your veterinarian for the best treatment. Worm infestation can reduce nutrient absorption, contributing to the inability to gain weight.
3) Disease – have your horse’s blood checked for liver or kidney disease, anemia, or Cushing’s (especially if your horse is older than 14).
Next, pay attention to two key factors:
1) Hind gut microbial population – The fibrous portion of forages (pasture and hay) is digested by the bacteria living in your horse’s hindgut (cecum and large colon). You can feed the best hay available, but if these microbes are not in good numbers, the fiber will be poorly digested. Fiber digestion results in calories for your horse. A good prebiotic (fermentation products), as well as yeast, will feed existing bacteria.
2) Calories – The most concentrated source of calories is fat, with more than twice the caloric value of carbohydrates or proteins. Therefore, you can feed less of it in order to avoid making your horse’s meals too large; remember the stomach is small – never feed meals larger than 4 lbs (1.8 kg) at a time to a full-sized horse.
Not all fat is the same, however. Choose sources high in omega 3s, such as:
- Ground flaxseed – feed at a daily total rate of ½ cup per 400 lbs (120 ml per 180 kg) of desired body weight. Flaxseed oil can also be supplemented at a rate of 2 to 4 ounces per day.
- Chia seeds – these do not require grinding but are best wet so they can plump up before feeding. Feed at a daily total rate of ¼ cup per 400 lbs (120 ml per 180 kg) of desired body weight.
- Camelina oil – add 2 to 4 ounces per day
- Hempseed oil – a good source of the anti-inflammatory omega 6 known as gamma linolenic acid. Add 2 to 4 ounces per day.
If your horse is not used to these fatty foods, start slowly with 1 tablespoon (15 ml) per meal, building up to the desired amount. If your horse is heavily exercised, additional oil can be fed. Rice bran oil or organic canola oil can be fed in addition to a high omega 3 oil, offering 1 cup of total oil per day (may increase up to 2 cups for a heavily exercised horse). Take a month to allow your horse to get used to this high level since it takes a while for the liver to adapt to large amounts of fat. Avoid corn, soybean, and wheat germ oils – these oils are high in linoleic acid (an omega 6) which is pro-inflammatory.
Don’t forget the B vitamins
B vitamins are involved in many functions that promote a healthy body:
- Energy (caloric) derivation from carbohydrates, fats, and proteins
- Gastrointestinal health, promoting digestion and absorption
- Protein synthesis to build body tissues
- Healthy red blood cells to deliver oxygen to tissues (to metabolize nutrients)
- Appetite improvement
Allow 24/7 grazing
Horses are meant to graze all the time, all day, and all night. Never let your horse run out of forage (pasture and/or hay). He needs to chew to produce saliva; this neutralizes the steady secretion of acid in the horse’s stomach. Forage free-choice also keeps the digestive tract musculature in good tone. Furthermore, the cecum requires forage for it to void its contents. By having pasture/hay available 24/7, your horse will self-regulate intake, the stress hormones will subside, and behavior will become more natural and receptive.
A variety of grasses will boost protein quality, but also offer alfalfa (a legume) to provide additional amino acids that promote muscle development as well as add calories. Never feed more than 50% alfalfa; too much can lead to intestinal stones. Cereal grains such as oats or barley offer additional protein; however these should be avoided for horses with metabolic issues. Other high-protein whole foods to consider are:
- Split peas or pea protein isolate
- Hemp seeds or hemp seed fiber
- Colostrum – also supports digestive tract health and immune function
- Copra meal (coconut meal)
- Pumpkin seeds
- Black oil sunflower seeds (in moderation due to high linoleic acid content)
- Whey protein
Underweight is not a normal state for any horse. Rule out health problems, and then feed a nutritious diet while paying attention to the hindgut microbial health, providing non-inflammatory fats, and offering quality forage at all times (free-choice).
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