Nutrition for the Older Horse

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Written By Kris Hiney 

 

With proper care, today’s horse owner can expect to have their equine companion for 20 to 30 years. Advances in veterinary care, parasite management and nutrition, allow us to sustain horses much longer than what would be observed in the wild. With proper attention to their nutritional needs, even the body weight and the condition of the horse can be maintained in a very good state. So what types of changes in the diet of the older horse should you address?
First of all, when should you begin treating your horse as an “old horse”? Typically horses older than 20 years are considered to be aged, but this may vary from horse to horse. Visual signs of aging include a loss of body weight, a loss of muscle mass over the top line of the horse, graying around the eyes and muzzle, and stiffening of the joints.
However, one of the most fundamental changes in the older horse is an alteration in its teeth and its ability to masticate its feed properly.  Horses’ permanent teeth begin quite long, (4-5 inches), with only a portion of the crown visible in the oral cavity. The teeth continue to erupt throughout the horse’s life as the crown of the tooth is wore down by grinding against the opposing teeth and the forage the horse consumes.   As a horse ages, continual grinding of its feed wears down the surface of the horse’s tooth. Eventually as this process of tooth eruption and wearing away of the crown continues, an old horse will essentially “run out” of teeth. Examination of the molars and premolars of elderly horses may show a very short molar in comparison to a younger horse. The root of the tooth may become less stable, resulting in a loss of teeth. Teeth remaining in the jaw which are unopposed grow into the remaining space and can press directly against the gums.
An older horse’s mouth may not only be less functional but quite painful as well. Attention by a veterinarian or equine dentist is imperative to insure that any such problems are addressed. However, no veterinarian or dentist will be able replace a horse’s lost teeth. In that case, the diet of the horse must be altered.
 Proper chewing is imperative to allow a horse to digest its feed. Because the base of the horse’s diet is forage, mastication is necessary to disrupt the tough cell wall of the plants. Without proper chewing, enzymatic digestion of the feed in the small intestine will also be limited.   With the horse unable to digest its feed to the same extent, the amount of feed that used to be able to support a horses’ energy needs is no longer enough — much of the energy content of the feed is actually lost in the feces.   The type of feed offered to the horse must now be much more digestible with less work by the horse!
Most major feed companies manufacture diets designed for aged horses. These feeds are typically pelleted or extruded, which eliminates the need of the horse to perform much chewing. Horse owners can make their senior citizens’ job even easier by wetting the feed to create a meal of mash-like consistency. Often these feeds can represent the sole component of the horse’s diet as they contain forage/ roughage, but in a form that is ground or finely chopped. They also contain feedstuffs that are highly digestible and calorically dense.
Fats provide a great deal of energy (2.25 x more so than carbohydrates), are highly digestible and are palatable to the horse.  You may also see different types of fiber sources added that are also easily digestible such as beet pulp, citrus pulp, rice bran, etc. These fiber sources are rapidly fermented by the horse and are safer to feed than providing your horse a large amount of starches and sugars.    Molasses added to feed does serve the purpose of increasing palatability and, thus, intake in horses.  If your older horse has a history of insulin resistance or metabolic syndrome, avoid feeds which contain a substantial amount of molasses.  It may be necessary to try several feeds to determine which your horse finds most acceptable and will readily eat.
Hay cubes can also provide a form of forage that an older horse can readily consume. Again, if your horse has trouble chewing the hay cubes, they can be moistened for easier consumption. If you are feeding horses this way in the winter, be sure to not offer the horse more feed than he can consume before it freezes. In addition, broken teeth may be more sensitive to cold and make him further reluctant to consume his feed!
Beyond an older horse’s lack of teeth, there may be some evidence that they simply do not digest feed in their intestines as efficiently as younger horses. It is even more important that these horses receive a balanced diet that can meet their energy, amino acid, mineral and vitamin requirements.  However, don’t go overboard and begin to randomly supplement your horse indiscriminately.
If he is housed with other horses, he may lose status in the social hierarchy as he ages. This could greatly affect his access to feed and should be carefully monitored.
Older horses frequently suffer from arthritis as well. Certainly, if your horse is uncomfortable or in pain he will be less likely to have a good appetite. While long term administration of NSAIDs may help to eliminate your horse’s pain, it may also cause an increased risk of ulcer formation. This will only further discourage the horse from eating. Alternatively, omega-3 fatty acids have been reported to decrease lameness scores and inflammation. Thus, feeding a source of n-3 fatty acids may keep your older horse more pain free with less gastric disturbances.
Finally older horses may be at an increased risk of disease transmission due to an age-related decrease in their immune system. It is important to provide an environment that is as stress free as possible for your horse to maintain good health.
Following these tips, as well as regular vaccinations and deworming schedules will help your horse have a good chance of reaching its 30s!

Preparing for the Breeding Season

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Written By Dr. Kris Hiney
While breeding season may be the last thing on anyone’s mind at this time of year, it will be coming soon. Now is the time to ensure that your mare or stallion is going to be at their optimal reproductive efficiency. While much of a mare’s or stallion’s fertility depends on other factors such as age, condition of reproductive organs, etc., there are some basic management steps we can take to ensure that as few cycles of inseminations are needed to get a mare pregnant. Multiple breeding attempts can quickly outstrip the original stallion breeding fee and be a significant cost to the mare owner. Often we forget that every shipment of semen may be an additional cost, followed by extra veterinary fees, mare board, etc. Therefore it is in the mare owner’s best interest to have her in optimal condition before the first breeding attempt ever occurs.
So how do you prepare your mare and stallion in January to begin breeding anywhere from February to mid-summer? The easiest place to begin is to look at your horse’s body condition score. For a mare, we want her to be at a body condition score of at least 5 or 6 (see “Too Fat, Too Thin, or Just Right”). A mare in this condition would be a moderately fleshy mare whose ribs are covered by fat, has evidence of fat deposition behind her shoulder and over her tailhead, and whose back is level. Mares that are a higher condition score than that may still have no problem getting pregnant, but are unnecessarily obese. This may result in more wear and tear on her joints. Additionally, as there is no increase in reproductive efficiency, maintaining a mare in too high of condition may just be a waste of feed costs. Furthermore, if she has chronically been obese with localized fat deposition, she may even be at risk for metabolic syndrome or insulin resistance (see Equine Carbohydrate Disorders, Part 3: Metabolic Syndrome).  If your mare is diagnosed with metabolic syndrome, it is important to correct her metabolic profile and manage her carefully through the breeding season. Altered hormonal profile can impair her ability to become pregnant and certainly extra weight in a laminitic mare may increase her level of pain.
If we look at the opposite condition and the mare is too thin, she will need more cycles to settle compared to a mare at adequate condition. She also may take longer to return to normal cyclic activity following winter anestrous (when mares cease to cycle due to the shorter day length). Thin mares’ conception rates may be lower, and if she foals in a thin condition, she may take longer to begin cycling again. With so many negative effects of trying to breed a thin mare, one of the easiest ways to increase reproductive efficiency is to put weight on your mare!
Stallions also use more energy in the breeding season due to the increase in their activity levels. Stallions which breed mares in an intensive live cover breeding system will of course need more energy than a stallion which is bred only once every other day. Stallions which are more extensively used would have energy requirements similar to a light to moderately exercising horse, and their maintenance requirements will also be elevated (see “Energy for Work”).  Typically, stallions are simply more active during the breeding season as they exhibit their normal sexual behavior. Ideally, stallions should be maintained in a body condition score close to 5 throughout the breeding season.
Beyond just meeting a stallion’s energy requirements, feeding of Omega-3 fatty acids may help improve his reproductive efficiency. In a study by Harris, et al, published in 2005 in Animal Reproduction Science, stallions supplemented with dietary Omega-3 fatty acids increased their daily sperm output.  Furthermore, there was an increase in morphologically normal sperm in the supplemented group.  The greatest response was seen in the stallion with initially the most morphologically abnormal sperm. In this study, one stallion who was considered to be a “poor cooler” improved his post cooling progressive motility from 23 to 38% in a 48 hour test cool. Therefore, supplementation of Omega-3 fatty acids may be a valuable tool in improving the reproductive characteristics of sub-fertile stallions.
Basic guidelines for increasing body weight and condition in horses are really no different for the broodmare or stallion than in other classes of horses. The quicker the gain is needed in the horse, the larger the increase in calories which must be offered daily. If you only have two months to get your mare in condition, you need to increase her energy intake by 30-40% to increase her body condition score by one number. If we have three months, which may be more realistic, the energy requirements increase by 20-30%. Remember, however, if you are trying to accomplish weight gain during the winter, she may also have an increase in energy requirements due to her need to thermoregulate. This will make weight gain more difficult. To add calories quickly to the diet, look for a fat-added feed that will be digested quickly and efficiently.  Remember that fat offers 2.25 x the calories that will be in grains which consist primarily of simple carbohydrates. Fat will also disrupt the metabolic profile of the horse to a lesser extent than a diet high in sugars and starches.
Of course, beyond caloric intake, always ensure that your breeding horses are consuming a complete balanced diet in respect to all nutrients, have good health care and are suitable candidates for breeding. Breeding horses is a big responsibility in terms of the care and well-being of the mare, stallion and the subsequent offspring.