When is a horse considered “aged” or a “senior” with respect to nutrition? At 15? At 20? Many nutritional studies conducted on older horses have arbitrarily used 20 years of age as the threshold for “aged” or “senior” The NRC 2007 suggests three ways in which “old age” can be defined, which are listed below.
- Chronologic – number of years from birth
- Physiologic – the decline in physiologic functions as the threshold for old age
- Demographic – reflects an age-group population within the whole horse population.
The best way to define this population of horses may be a combination of chronological age and physiological signs of aging. As horses age they go through several changes that affect how and what you should feed them. Some physical signs of aging are:
- Dental disease and/or loss of teeth can cause chewing to become difficult and even ineffective. Worn incisors will make it difficult for horses to graze. Worn or damaged molars cause difficulty grinding feed. Worn molars cannot chew hay and the horses have a difficult time swallowing and digesting the hay. Alternative forges like hay cubes and pellets can be fed to horses with poor teeth. Sugar beet pulp and soybean hulls can also be fed to increase fiber intake. Grains, if fed, should be well processed (extruded, pelleted, micronized or steam flaked).
- The hindgut loses some of its ability to ferment fiber. A reduction in fiber fermentation means that older horses receive less nutrients from forage resulting in higher quality forages being required. Alfalfa hay and good quality grass hays are preferable to stemmy and mature hays that have tougher fiber to ferment.
- The small intestine loses some function - Older horses find it harder to digest protein in the small intestine. In addition, some older horses with reduced liver and kidney function find it difficult to excrete waste products associated with eating too much protein. Therefore, the key to feeding older horses is to use high quality protein from sources like alfalfa, soybean meal and canola meal without oversupplying their requirements. Aged horses lose body condition and muscle along the topline due to less efficient processing of certain nutrients in the older horse, most notably protein. Commercial senior feeds has improved the amino acid balance to help reverse such changes.
- Older horses are prone to Cushing’s Syndrome. Cushing’s horses often lose muscle mass to a higher degree than a normal aging horse. Again, improving the amino acid balance (not just feeding MORE protein) can help reverse the loss of or maintain muscle mass.
- One of the most obvious changes in an older horse is loss of mobility. For these horses, maintaining them in pastures/paddocks where feed and water sources are reasonably close together will help so the old ones do not need to travel long distances. If the senior horse is maintained in a herd, they should be evaluated on a continuous basis because most will fall down the pecking order and are more easily bossed around. This results in the aged horse eating less feed.
- Loss of body score (body condition or body fat) is related to all of the above issues. Many older horses require more calories in the form of highly digestible fiber from sources like beet pulp, soy hulls and dehydrated alfalfa meal. In addition, dietary fat helps with weight loss.
The total diet, hay and grain combined (dry matter basis), should contain 12-14% high quality protein, 03. – 0.4% phosphorous, 0.6 – 0.8% calcium and added Vitamin C.
- Aged horses that are healthy with a BCS of 5 to 7 require 1.5-2.0% of their BW DM/day of good quality grass or legume mix hay. Typically, no grain is required but if desired or needed, choose one with restricted starch/sugar and contains added fat (4-7%). In these horses, forage based pellets or cubes could replace 10 to 50% of the long stem/chopped forages.
- Aged healthy, thin horses with a BCS < 4 should be fed 1.5-2.0% BW DM good to excellent quality grass or grass/legume mix hay. A grain based concentrate formulated for the aged horse with 12-14% CP and 4 to 7% fat should be fed at 0.5-1.0% of BW. Starch and sugar should be minimized if the horse is prone to laminitis or has PPID. Forage based pellets or cubes can be used to replace 10-50% of the long stem/chopped forages.
- If the horse can still eat hay:
- Use higher fat, and/or heat-processed feed (like extruded or pelleted). Extrusion/heat-processing increases foregut digestibility.
- Assure adequate intake of all other vitamins and minerals.
- Offer free-choice vitamin/mineral mix designed for horses eating grass hay.
- If the horse cannot eat hay (leaves wads of hay by feeder):
- Feed complete feed with highly digestible fiber. Fiber sources include beet pulp, dehydrated alfalfa meal and soy hull.
- Assure high quality sources of protein, vitamins and minerals.
- If the horse cannot chew well, one can make a slurry of complete (and/or) extruded feed.
- Feed at least 3 times a day.
- Total intake should be 1.5 – 2.0% of horse’s body weight (15 – 20 lbs. For 1,000 lb. Horse)
Old horses are valuable and literally have a lifetime of experience under their ‘girth’. We want to do our best to keep them around as long as possible, which requires good veterinary, farrier and dental care. A solid foundation of good nutrition is required for maintaining our old friends.