At what age should a horse be transitioned to a senior feed? There is no single answer to this question because there is no distinct age that a horse is considered old.

Chronological age, or age in years, is ultimately much less important than physiological age. As horses age, they undergo physiological changes that make digestion and absorption of nutrients more difficult; however, these changes don’t occur at the same rate in all horses.
Most readily apparent in the aging process is the wear and loss of teeth. As teeth are worn down and lost, a horse's ability to mechanically breakdown feed decreases. At the extreme end of the spectrum, we see this as an inability to adequately consume forage. Horses will often still attempt to eat forage and drop balls of partially chewed hay, known as quidding. In these cases, complete forage replacement is required.

Much less extreme, and easier to miss, is the slow reduction in the ability to mechanically breakdown feed in horses that aren’t yet quidding their forages. The mechanical breakdown of feed, which is accomplished through the grinding action of the molars, is necessary to decrease particle size which allows the horse to easily swallow forage, but also serves to increase the surface area available for the digestion process. With less surface area available for digestion, the horse cannot extract as many nutrients out of the feed.

A reduction in the ability to chew feed and, therefore, decrease in feed digestibility is further exacerbated by a reduction in the absorption capacity of the digestive tract as horses age. Simply put, less nutrients are available (lower digestibility due to decreased mechanical breakdown) and of those nutrients, less are absorbed from the digestive tract.

Depending on where a horse is in the aging process will guide nutritional needs. Some horses need total forage replacement at 20, whereas others might be happily eating forage and maintaining body condition on a ration balancer well into their 30's!  

Supporting Maximum Digestibility

Whether we are replacing all of the forage in the diet or simply supporting the aging horse that is still consuming forage, the goal is to maximize the amount of nutrients the horse digests and absorbs from the diet. Choosing products with a fixed formula that lists the ingredients used instead of broad terminology, such as "grain products" or "roughage products", allows you to evaluate the quality of the ingredients used, while also maintaining consistency in the diet.
Additional digestive support can be provided through pre- and probiotics, as well as added enzymes to maximize digestibility.

Prebiotics are nutrients that are not digestible by the horse, but provide key nutrients to the microbes in the digestive tract that breakdown fiber. Probiotics are live microorganisms that support the beneficial bacteria in the digestive tract of the horse. Pre- and probiotics together help stabilize the microbial population in the digestive tract, while also increasing digestibility of feedstuffs, particularly fiber.

Adding digestive enzymes to the feed can be particularly beneficial for aging horses, as their capacity for digestion diminishes with age. Enzymes added to the feed helps bolster the enzymes naturally produced by the horse. Digestive enzymes break down nutrients into the small component parts that are absorbed and utilized by the horse.

Total Forage Replacement

Total forage replacement is required once a horse can no longer adequately consume forage due to wear and loss of teeth. For these horses, we want a feed that can replace all of the forage in their diet, while also providing the other nutrients necessary to support health. Look for feeds that are high in crude fiber (15%+) and formulated with the needs of the senior horse in mind. Along with high crude fiber content, look for sources of highly digestible fiber in the ingredient list, such as beet pulp, soy hulls and alfalfa.

A soaked hay pellet or cube can be a good addition to the diet when regular forage can no longer be consumed, but hay pellets or cubes alone will not provide all of the necessary, essential nutrients (amino acids, vitamins and minerals) to meet dietary requirements and support the health of your senior horse.

When replacing all of the forage in your horse’s diet, aim to feed at least 1% of their body weight split into multiple smalls meals throughout the day.

For a horse still consuming forage, it is important to pay attention to the minimum recommended feeding rate for a senior feed. Senior feeds are intended to replace forage, so they are designed to be fed at high volumes and, therefore, have a lower concentration of essential nutrients to ensure that these nutrients are not supplied in excess when feeding large volumes. Feeding a senior feed to a performance horse below the minimum recommended feeding rate will result in underfeeding key nutrients that support health and performance.

Ultimately, remember that age is just a number! Routine dental care and careful observation of changes in the older horse’s body condition will help determine when a fiber replacement feed is needed. Horses can benefit from a feed high in digestible fiber sources, as well as added digestive support technologies, like probiotics and enzymes, before they require total forage replacement, but many feeds that are not marketed as “senior feeds” fit this bill.

Complete Feeds by Tribute®​ Equine Nutrition


Nicole Rambo, Ph.D.