As horses grow older, their nutrient needs change. This might be due to bad or missing teeth, changes in metabolism or less efficient digestion. Some horses become thin, while others gain weight and become prone to laminitis. Some develop problems such as Cushing's disease, insulin resistance, failing kidneys, or impaired liver function.
Importance of balance
Amy Gill, PhD, an equine nutritionist based in Kentucky, USA, says it is important for an older horse to have good-quality protein with the right amino acids. "Make sure the diet is highly fortified with vitamins and minerals, and very digestible sources of fiber," says Gill. “Don't feed overly mature, coarse hay that's hard to chew and does not contain adequate nutrients.
"In general, a healthy older horse that doesn't have metabolic problems has nutrient requirements a little higher than a mature horse in its prime," she says. "An older horse's requirements are very similar to those of a young, growing horse. Digestive efficiency is reduced in older horses. Like older humans, many of them get thin. They are in a more catabolic state – metabolising muscle tissue."
The old horse needs more feed, but it must contain all of his nutrient requirements; do not increase calories just by adding more grain. He needs a concentrate with less grain and higher levels of soluble fibre and fat.
"Find a fat source that has a high omega-3 fatty acid, like a flax oil blend," Gill says. "This helps with immune response and is also a pro-anti-inflammatory," meaning prostaglandins (hormones that regulate cellular activites) produced in the body will tend to be the anti-inflammatory type rather than inflammatory. Omega-6 fatty acids (found in grains) tend to be proinflammatory.
She also recommends products containing small amounts of direct-fed microbials, such as yeast and Lactobacillis, since these are beneficial if the large intestine is not functioning as well as it used to. Vitamins E and C are also helpful since they are powerful antioxidants, says Gill.
Avoid starch and sugar
Gill says the main thing to watch for in older horses, is that many of them are sensitive to starch and sugar; 70% of horses over age 20 have Cushing's disease. "If a horse has Cushing's disease or insulin-resistance problems, you can't just add calories to the diet with straight grain," says Gill. "We don't recommend that at all. If a horse is on hay, make sure there's not too much soluble carbohydrate or NSC (non-structural carbohydrates) in the hay."
For a horse with Cushing's disease or insulin resistance, she recommends a lower quality hay (fewer NSC) and supplementing with vitamins, minerals, and protein that the hay might lack. "You choose the lesser of two evils; you don't want a horse to not have anything in front of him to eat, so you use a lower-quality hay he can nibble on all day rather than a couple small flakes of good hay," she states.
A healthy horse can handle a better quality hay, but you don't want to precipitate an insulin resistance problem by overfeeding starch and sugar.
"You can feed a good-quality, low-starch, high-fat and fibre concentrate like a senior feed," says Gill. "But an important thing for horse owners to know is that even the senior feeds are not good choices for horses that are insulin resistant or have Cushing's disease. You need to look for a product that is low in NSC, so the total diet (forage and concentrate together) will be no higher than 10% NSC."
You must be careful all through a horse's life to make sure he does not become insulin resistant later on.
"Don't overfeed the pregnant mare on starch and sugar, nor the foal, and on down the line," Gill warns.
Dental issues
Stephen Duren, PhD, an equine nutritionist with Performance Horse Nutrition in Weiser, Idaho, says when you start planning a diet, start with forage.
"If an old horse, because of poor teeth, is quidding (dropping wads of partly chewed feed from his mouth) or not getting feed adequately chewed, we have to 'chew' it for him," says Duren.
An older horse that's not keeping his weight might not be getting enough fibre, says Kathleen Crandell, PhD, superintendent of Virginia Tech's Middleburg Agricultural Research and Extension Centre.
"The biting surface of his teeth may have changed and become wavy, or he's lost teeth and can no longer grind forage properly. He may do fine on green grass, but loses weight when you feed hay in winter." This is when you need to use alternative forages such as hay cubes or chopped forages –something in which the breakdown process has already started, so teeth don't have to do it all.
"Ultimately some horses need pellets containing forage that is ground up and doesn't need much chewing," says Crandell. "There are benefits in using chopped hay or hay cubes, since there's still some length in that material, which helps keep the digestive tract functioning more normally than with finely ground forage."
If a horse's teeth are so bad you must resort to pellets. Duren recommends completely covering the pellets or cubes with water so they soak it up and become soft. "Once the feed is fully moist, I don't add any extra water; the mass of pellets or cubes just grows in bulk as they take on water," he says. When using alternative fibre sources such as beet pulp, these are soaked also.
Make a mash using hay pellets and add wheat bran or a senior feed. Again, forages are most important and a senior product alone might not be enough.
Defining old-age
Duren says there's an emotional definition of when a horse is old – when he retires from a career. He might be put out to pasture just because he's no longer being ridden regularly.
"There's also a nutritional definition of old, when he can no longer eat a normal diet and maintain body weight," says Duren.
Aging rate is affected by genetics and lifestyle. "If he had good care all his life and was never used hard, 'old' may be mid-20s or early 30s," says Duren. "However, if a horse went to every branding and to team roping events every weekend, he may be arthritic and have old injuries."
An older horse might lose weight because he's stiff and not as aggressive in the herd – he's dropped down in the pecking order and has been chased away from the hay. Dental problems and loss of teeth can also be a factor: In many ways a horse is only as "old" as his teeth. Some horses' teeth develop problems sooner than others. – www.thehorse.com
