There is little more precious than the old horse around the place. Theseoldies are often the dependable horses that look after a novice rider or give a young horsesome confidence when out on the trails. Because they are so valuable and literally have alifetime of experience under their 'girth', we want to do our best to keep them around aslong as possible. While good veterinary, farrier and dental care are important formaintaining the long term health of your geriatrics, their health care should always bebased on a solid foundation of good nutrition.

As horses age they go through several physiological changes that affect how and what youshould feed to keep them as healthy as possible. Detailed below are four of the mostimportant of these changes and how you can best manage them from a feeding and nutritionperspective.

1. Teeth Wear
As a horse gets older its teeth eventually stop growing and will gradually start to weardown until chewing becomes difficult or ineffective.

Worn incisors (upper and lower front teeth) make it difficult for horses to graze asthe top and bottom incisors need to make good contact in order to shear the pasture off. Ifa horse has worn or damaged incisors, but its molars used for grinding feed are still ingood condition, feeding hay will allow the horse to readily get the forage into its mouthsimply using its lips and tongue (no need for incisors). Once it is in the mouth the horsecan use its molars to grind the forage as normal.

However, worn or damaged molars mean grinding feed also becomes difficult, so feedinghay is not a good idea as the horse can't chew it enough to be swallowed and digested. Feedforage that has already been extensively chopped up or processed. Forages like short choppedchaff or soaked hay cubes and pellets are good alternate forages for horses with noeffective molars. Fibres like sugarbeet pulp and soybean hulls may also be used to increasean old horse's fibre intake when they are no longer able to graze or eat hay.

If you are feeding grains, the grains should always be well processed (boiled, extruded,pelleted, micronized or steam flaked) before being fed so the grain can still be digestedeven if they are not effectively chewed. Never feed whole grains to older horses that can'tchew very well.

2. Hindgut loses some function
It is thought that as horses age their hindgut loses some of its ability to ferment fibre.This is likely due to changing populations of bacteria in the hindgut associated withageing. A reduction in fibre fermentation means that older horses get less of the goodnessout of forage (which partly explains why old horses need to be fed more to maintain theirbodyweight).

Because the hindgut is not as effective at fermenting fibre, there should be a focus onfeeding high quality forages with fibre that is easy to ferment. Lucerne/alfalfa hayand good quality, soft meadow/pasture hays are preferable to stemmy and mature hays thathave tougher fibre to ferment. High energy 'super fibres' like sugarbeet pulp and soybeanhulls are also excellent source of fibre for older horses as they are very easy to fermentin the hindgut.

Some pre‐biotics like Alltech's Yea‐Sacc® 1026 live yeast culture (which is used in manydifferent feeds and supplements) have been shown to improve the digestion of fibre in thehindgut, so it may make a useful contribution to the diet of aged horses.

It is also likely that the hindgut of older horses doesn't support the production of B‐vitamins as well as a younger horse's gut does. Thus it may be necessary to supply moreB‐vitamins in the diet. FeedXL takes this into account and has raised B‐vitaminrequirements for aged horses. The production of biotin may also be reduced in older horsesso it may need to be added to the diet of older horses. For more information onsupplementing with Biotin, read FeedXL Newsletter #2: Biotin for hoof health? Or $ down thedrain.

As horses age they also find it harder to absorb phosphorous from the hindgut. Again FeedXLtakes this into account and has raised phosphorous requirements for aged horses.

3. Small intestine loses some function
In studies we conducted at The University of New England we found that an older horse hadmuch lower concentrations of carbohydrate digesting enzymes in its small intestine thanyounger horses had. While it was a limited study with small horse numbers, it is likely thatas horses age their ability to digest carbohydrates like starch in their small intestine isreduced. This means digesting feeds like grains becomes difficult (which alsocontributes to older horses needing to be fed more to hold their bodyweight).

So, aged horses should always be fed cooked grains that have been boiled, extruded,pelleted, micronized or steam flaked so that the starch they contain is easy to digest. Ifyou suspect your horse has difficulty digesting grains look for a feed that has added starchdigesting enzymes or use a supplement that contains enzymes like amylase andamyloglucosidase to help with the digestion of the grains.

Older horses also find it harder to digest protein in the small intestine and somewith reduced liver and kidney function can also find it difficult to excrete waste productsassociated with eating too much protein. So the key to feeding older horses protein is touse high quality protein from lucerne/alfalfa, soybean, lupins, canola meal or fababeans to satisfy without oversupplying their requirements.

4. Mobility is reduced
Perhaps the most obvious change in an older horse is some loss of mobility. Becausethey can't get around so easily, try to have them in pastures that have the feed and watersources reasonably close together so they don't have to travel long distances for feed orwater.

You will also probably find that if they are kept in a herd they will slowlyfall down the pecking order as they become easier to boss around. If this happens you shouldfeed your old horse separately to avoid him having all his feed pinched by the youngerhorses higher in the order.

Take home message ...
If you keep in mind the physiological changes occurring in your horse as it ages it willhelp you to adjust feeding accordingly. Feeding forages that are easy to chew and digest,grains that have been well cooked, increasing the intake of nutrients like phosphorous andB‐vitamins, providing good quality protein, and being aware of any mobility issues that mayaffect feed intake will help keep your oldies happy and healthy for years to come.

Dr. Nerida Richards (PhD) is Australia's foremost expert in Horse Nutrition. This article iscourtesy of FeedXL DIY Diet Planner forHorses. If you would like be among the first to receive FeedXL newsletters thenplease consider subscribing to FeedXL.

See more horse-feeding articles in The Feed Room.

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