For the scientific community, a horse is regarded as being aged after the age of 20. Nevertheless, depending on the physiological stage (is he used for breeding? ) and the horse’s past (periods of malnutrition, strenuous exercise …) the onset of old age can be more or less early, and more of less difficult to live with. A review of feeding the aged horse, that’s to say a report on current scientific knowledge, was recently written by researchers from Great Britain and the United States. We offer here a summary of that review.
What happens when the horse ages?
- DIGESTIVE AND GASTRIC HEALTH,
- The diversity of the intestinal microbiota decreases, which can thus mean that susceptibility to infections and inflammation is increased.
- The ability to digest phosphorus, proteins and fibres drops when parasitism and dental health are not monitored. Nevertheless, when horses are correctly wormed and their oral cavity receives regular attention, a correlation between age and the ability to digest ceases. Thus, the drop in the ability to digest in aged horses would seem to be mainly related to parasitism and dental problems.
- ENERGY REQUIREMENTS AND CONDITION
- The majority of aged horses do not seem to have difficulty maintaining condition. Likewise, the loss of muscle mass seen with ageing is due principally to a decrease in physical exercise. Light exercise indeed maintains muscle mass in elderly horses, if, in addition, they are supplemented with essential amino acids (lysine et threonine). In the aged horse, loss of condition should therefore be looked upon as a warning of a health problem: dental, hepatic, renal or even metabolic. Indeed, horses suffering from Cushing’s disease for example, will lose a huge amount of muscle.
- When the weather is cold (and in particular wet and cold), aged horses require more energy to maintain their body temperature than younger ones. It has also been demonstrated that age disturbs thermoregulation during exercise. Aged horses therefore have more difficulty in regulating their body temperature, which signifies that their feed requirements may be increased during the winter. In the summer, they may suffer from the heat, which can notably reduce their appetite.
- IMMUNITY AND HEALTH
- The immune system deteriorates, which affects response to vaccination (antibody production) and so vulnerability to infections with age. This is particularly related to the fact that elderly horses have lower concentrations of vitamin C in their blood serum than younger horses. Likewise, there exist a phenomena, called “inflamm-ageing, which occurs when the horse ages. This signifies that the older the horse becomes, the more he exhibits factors of chronic inflammation. Chronic inflammation is associated with the development of metabolic diseases and osteoarthritis.
- The horse’s teeth erupt outwards throughout his life, and the risk of dental problems are accentuated with age. “Quidding (dropping partially chewed food out of the mouth), repeated bouts of sinusitis, weight loss, choke (food stuck in the gullet), loss of appetite, colics (especially impaction), changes to the consistency of the droppings, as well as the presence of excessively long fibres in the droppings.
- Orthopaedic diseases, and in particular, osteoarthritis can affect the horse’s will to feed, especially from the ground.
How should the aged horse be fed?
Generally, it is advised to regularly (between once a week and once a month) weigh or evaluate the condition score of the horse, an optimal condition score is situated between 2.5 and 3.5 out of 5. It is also wise to follow the worming programme suggested by your vet and to organise regular dental care (once a year). Finally, when the aged horse is lodged in a group, providing sufficient feeding bowls/hay racks so that he is able to feed is recommended, because aged horses are often at the bottom of herd hierarchy and take longer to finish their food. In the most extreme cases, separating the aged horse at feeding times is necessary.
It is also important to give the aged horse:
- A forage based diet, between 1.5 and 2.5% (dry matter) of bodyweight (live-weight), which equates to 8-14kg of hay for a 500kg horse,
- A concentrate feed fed divided into a number of small meals (so as not to exceed 100g of starch for 100kg of bodyweight per day) containing quality protein sources (soya, luzerne), rich in essential amino-acids (lysine, threonine),
- A supplement rich in antioxidants, such as vitamin C, vitamin E and selenium, which will play a part in immunity and regulate inflammation.
- If the horse is overweight but otherwise in good health,, restricting hay intake to 1.5% of bodyweight (so 8kg for a horse weighing 500kg), and accompanying it with a vitamin and mineral supplement is recommended.
- If the horse is overweight and suffers from a metabolic disorder, in addition to the previous recommendations, it is advisable to avoid grazing and to feed hay with a soluble sugar content lower than 10%. Finally, in this case, vitamin E supplementation can be increased up to 8-10g per day. In order to slow forage intake and avoid boredom, feeding the hay using a small-holed haynet is also suggested.
- If the horse is losing weight but in good health, gradually raising the energy value of the ration by firstly increasing the quantity of hay available is recommended. In the concentrate feed ration, adding 50ml for every 100kg of bodyweight per day of good quality vegetable oil is also advocated. We equally recommend administering a pre-pro-postbiotic supplement which will support the intestinal microbiota.
- If the horse has dental problems despite veterinary care, be aware that fresh grass is easier to chew than hay. Even in this case, the horse’s diet must be chiefly made up from forage. It is advisable to choose leafy hay, haylage or chopped hay. Particular care must however be taken with chopped hay as the short fibres can accumulate in the spaces between the teeth (diastema). In any event, restricting the length of fibres in order to limit colics due to impaction and increase the ration’s digestibility is recommended. If the teeth are in a very bad state, soaking foods that are rich in chopped fibres is proposed. This will however reduce the amount the horse is able to ingest at each meal, which will therefore necessitate the fractioning (into 4 to 5 meals a day) of soaked food.
- If the horse suffers from osteoarthritis, especially cervical osteoarthritis, it is advisable to feed at height (for example attach the feed bowl to the top rail of the paddock fence) and to not feed the hay too high (avoid highly strung haynets). In addition to regular veterinary attention we also advise providing chondroprotective agents.