Most people associate the word “diet” with restricted food intake in order to lose weight. The word diet, however, involves four elements: the food sources, their preparation, and the amount and frequency they are consumed. So, the word diet itself does not imply any restrictions of intake amounts or food sources; that is a misconception created by the social media and the many diets to ‘lose weight’ being advertised. For example, if one eats huge amounts of sweets and other carbohydrates daily, this is that person’s ‘diet’, without thinking about the consequences in the body condition or any possible metabolic diseases that may come after a while. To avoid such confusion, ‘diet’ can be interchanged with the expressions ‘feeding program’ or ‘feeding plan’, and that is exactly what it means.
An ideal feeding plan (diet) should assure the best health and physical condition of a person or an animal. The proper diet for a horse may vary due to several factors:
- Physiological stage, such as maintenance (a non-reproducing, non-working, adult horse that is not expected to gain weight), growth and development, and reproduction (breeding season, pregnancy, and lactation).
- Body condition (related to appearance of fat deposits throughout the body and, therefore, correlated to weight).
- Physical activity (exercise).
- Individual needs.
Based on these factors, a horse owner/manager must consider three important elements in designing a horse’s diet: Total intake, body condition, and the nutrients more highly required by each horse.
- Total intake: Each horse should eat a daily amount of food, consisting of forage, possibly supplemented by concentrate feed or grains (cereals). As a rule of thumb, a mature horse should eat 10% to 12% of his body weight in green (fresh) forage daily, containing about 13% of dry matter; or 2% to 2.3% of his body weight in dehydrated food daily (including hay, grass cubes or pellets, grain, etc.), containing 85% to 90% of dry matter. When a horse grazes in a good quality pasture, either permanently or a few hours daily, it is difficult to calculate the actual intake of green forage and, thus, the amount of dehydrated food to be supplemented with (e.g., concentrate feed).
Dry matter is a crucial parameter to considered because the more water (humidity) in a food source (for example, fresh grass), the more diluted the nutrients are per weight unit. That is why, to fulfill his nutritional needs, a horse needs to eat more fresh grass, such as pasture or fresh-cut grass (in terms of forage weight) than when its hay version is offered.
Likewise, the higher the dry matter content in a food source, like in dehydrated sources (usually 85% to 90% dry matter content), the more concentrated the nutrients are per weight unit. So, dry matter and, thus, total nutrient content in 5 lbs. of fresh grass (e.g., Timothy) are five to six times lower compared to what is found in 5 lbs. of its hay version (e.g., Timothy hay). Likewise, if those 5 lbs. of fresh Timothy grass (85% humidity = 15% dry matter) are made into hay (14% humidity = 86% dry matter), the final nutrient content of this material can be considered the same, although the weight of the hay version will be only 0.87 lbs., due to the dehydration process.
- Young horses (expected to weigh 1,000 lbs. in average as adults):
A two-month old nursing foal will eat from 3.5 to 7 lbs. between hay and grains/concentrates (containing 85% to 90% of dry matter) daily, plus the mare’s milk, which, at this time, should be in peak production.
A four-month old foal still nursing eats from 7 to 10.5 lbs. between hay and grains/concentrates (with 85% to 90% of dry matter) daily, plus the mare’s milk.
An eight-month old weanling foal eats from 11 to 13.5 lbs. between hay and grains/concentrates (with 85% to 90% of dry matter) daily.
A twelve-month old horse eats from 12.5 to 18 lbs. between hay and grains/concentrates (with 85% to 90% of dry matter) daily.
A twenty-four-month old (not working) horse eats from 14 to 20 lbs. between hay and grains/concentrates (with 85% to 90% of dry matter) daily.
- Adult horses (1,000 lbs. average weight):
An adult horse at rest (horses being used for reproduction or horses that need to gain weight not included) eats from 15 to 21 lbs. between hay and grains/concentrates (with 85% to 90% of dry matter) daily.
A horse under light work (pregnant/lactating mares not included) eats from 16 to 23 lbs. between hay and grains/concentrates (with 85% to 90% of dry matter) daily.
A horse under heavy work (pregnant/lactating mares not included) eats from 18 to 28 lbs. between hay and grains/concentrates (with 85% to 90% of dry matter) daily.
A pregnant mare (during the last three months of pregnancy) eats from 17 to 23 lbs. between hay and grains/concentrates (with 85% to 90% of dry matter) daily.
A lactating mare (not at work) eats from 18 to 25 lbs. between hay and grains/concentrates (with 85% to 90% of dry matter) daily. This does not include the hay and grains/concentrate that her foal eats besides the milk.
Notes:
- The information above is applicable to confined horses and horses kept outside in areas without access to grazing.
- The intake of horses grazing in good pastures, either part-time or full-time, must be determined based on type and availability of grass and, based on their body condition, supplemented accordingly.
- The appropriate proportion of dry forage should always be higher than any supplements being used either grains (cereals) or concentrate feed.
- Body condition: This refers to the appearance of the horse based on how noticeable its bony structure is, and the location and aspect of the fat deposits throughout the body. Various scoring systems have been designed to evaluate a horse’s body condition, from which the best known was developed at Texas A&M University by D. R. Henneke, G. D. Potter, J. L. Kreider, and B. F. Yeates, and first published in 1983 as A scoring system for comparing body condition in horses. Their system includes 9 scores (from 1 to 9), each representing a specific body condition.
For this article, to help the readers apply the concept of ‘body condition’ easily while designing a feeding program for their horses, only three levels are considered: Thin, Normal/Ideal, Overweight.
- Thin: This is a horse which bone structures at the withers, spinous processes (bony ridge) at the back area, ribs, croup, hip bones, and buttock bones can be noticed under the skin by simply looking at the animal, because they are prominent. When the horse is seen from behind, there is no roundness from the croup toward the hip bones, but, conversely, looks angular with the bone structures clearly prominent. To the touch, fat tissue cannot be felt in these areas, but only bone under the skin. In a case like this, the more prominent and noticeable the bone structures in those areas appear, the worst is the body condition of the horse and, thus, the more urgently he needs to recover (gain weight).
Common causes for a horse to exhibit a thin body condition described here are: Being underfed (including starvation) and/or overworked for a long time, a mare being underfed during lactation, lacking one or more limiting nutrients in the diet, being sick or recovering from a long-lasting disease, having a metabolic disorder, being infested by internal parasites, suffering gastric ulcers, having tooth issues such as cavities and/or sharp edges on the premolars/molars, or a combination of these.
To help a horse improve this body condition (gain weight), any of the existing causes listed above must be corrected, first. His new diet should include abundant good quality forage, ideally a mix of grass and legume. If wanting him to gain weight fast, some grain/concentrate feed with 3% to 5% of fat in it should be added. Additionally, this horse should not be worked until there is significant improvement. Likewise, if it is a mare exhibiting this body condition, breeding her is not recommended, although, anyway, having her pregnant will usually not be accomplished.
- Normal/Ideal: Horses of all ages, at any physiological stage (including broodmares), and performing any work or equestrian sport should exhibit this body condition, with some variations depending on the type of exercise. Looking at the horse, his withers, spine at the back area, ribs, croup, hip bones, and buttock bones should neither appear bony nor prominent. Instead, they should look smoothly curved, but still defined, making the horse’s silhouette appear harmonious, and allowing the muscles of the neck, forearms, and hindquarters to be noticed. When the horse is seen from behind, roundness should be seen extending from the croup down to the hip bones that finally fuses with the thighs.
To the touch, those same areas (withers, spine at the back area, ribs, croup, hip bones, and buttock bones) should feel firm because of having some fat in between the bone and the skin. However, they should neither feel too hard due to the bone is felt under the skin, nor spongy due to the excess of fat.
Horses exhibiting this normal/ideal body condition, however, can be divided into two groups: svelte and robust.
Horses appearing svelte, still meet the description of the normal/ideal body condition, but do not look too muscular or beefy. To the touch, the fat being felt in between the bony areas described above and the skin is thin. This is the ideal body condition for young, growing horses, broodmares ready to be bred, adult horses in maintenance (a non-reproducing, non-working, horse that is not expected to gain weight), and horses that work long distances daily, such as training/competing in endurance, herding cows or sheep in big farms, pack horses, and equines used in trail rides mainly walking.
Horses appearing robust are more muscular and/or beefy than those appearing svelte. To the touch, the fat in between the bony areas and the skin feels thicker but not spongy. This is the ideal body condition for pregnant mares to foaling and for lactating mares (which can only be accomplished with a diet being adjusted at least monthly during the months of lactation and supplementing their foals with forage and grains/concentrate according to their growth), stallions during the breeding season, horses in training at any age, horses during the show/competition season (except for endurance competition), and adult horses at the time of being for sale.
Horses being trained or competing in speed sports such as racing (Thoroughbreds, Quarter horses, Arabians), street horse racing, rodeo disciplines such as roping and barrel racing, exhibit noticeable big muscles on the thighs, forearms, and chest. Those muscles are developed during the specific training for speed and supported with a diet that includes carbohydrates (from cereals) and fat. These two elements lead to storing Glycogen in the muscles that can be used as an immediate source of energy during the physical activity at peak speeds. Quarter horses for the halter classes also exhibit those same big muscles, although they are not trained and fed as for the speed sports; they are, actually, the ‘body builders’ of the equine species. After selective breeding, this is a trait transmitted by some bloodlines of the breed to the offspring; and in preparation for the competition, the animals are fed and exercised in ways that make those muscles more apparent.
On the other hand, horses being trained for sports where a combination of strength, agility, and moderate speed are required (e.g., dressage, jumping, gaited horses), also exhibit well developed muscles in those same areas, but they are less exaggerated and look more harmonious with the rest the body. Their diets include a mix of good quality forage supplemented with cereals and/or concentrate feed.
- Obese: This horse has too much fat tissue on his neck, barrel and butt, that the bone structures of these areas (withers, spine at the back area, ribs, croup, hip bones, and buttock bones) cannot be perceived to the touch, even when pressing the skin strongly with the fingers. Instead, there are packs of fat on different parts of these areas (that vary from horse to horse), adding new forms to the animal’s normal silhouette.
Those fat deposits are usually found: along both sides of the crest, sometimes extending down to the entire neck; the withers, which feels cushioned on the sides; behind the shoulder blades toward the ribs; the side rib areas, which besides being far to feel the ribs to the touch, scattered patches of fat can be found; the flanks, which, instead of having the appearance of a slight groove extending down from the hip bones and between the belly and the hindquarters, they look slightly round and feel filled with fat to the touch; and around the tailhead (where the tail meets the body), making it look bulky and feel from soft to hard to the touch.
An obese horse is not healthy under any circumstances and having reached this level is not acceptable. Besides being at high risk of developing different types of diseases, including laminitis,
The most common cause of obesity is overfeeding, especially with highly-energetic diets including grains (cereals) or concentrate feed that the horse does not need at the moment. Some pregnant mares tend to become obese easily due to the anabolic effect of the pregnancy hormones. ‘Easy keepers’ are horses with a slow metabolism that tend to obesity with similar diets offered to adult horses in maintenance. To prevent obesity in horses with this tendency, they should have diets based on forage, probably supplemented with low amounts of a low-starch and no molasses concentrate feed, when needed. Their body condition should be monitored at least weekly to make diet adjustments accordingly, and additional exercise may be required, either from the ground or under saddle.
To help an obese horse reduce the extra fat, its diet should be based on forages only (legume not included), complemented with additional daily exercise (not under saddle) that should be increased gradually in time and intensity. It usually takes three to four weeks to see the first results and six to eight weeks to bring the horse to a normal body condition. The best options to start exercising the obese horse are a mechanical hot walker, free lunging, and/or regular lunging.
(6-1a) about 3.1” tall (6-1b) about 3.1” tall
Minimal recommended body condition (moderately thin – score 4) |
Ideal body condition during the show season (between fleshy – score 7, and fat – score 8) |
- Some nutrients to keep in mind: According to their physiological stage and/or physical activity, some horses need a greater amount of certain nutrients to fill their requirements.
- To calculate diets for horses, the energy content in the feed sources is commonly represented as “Digestible Energy” (DE) and expressed in Megacalories per kilogram of feed (DE: Mcal/kg). Likewise, a horse’s daily requirement of energy may be expressed in Megacalories of digestible energy.
An adult horse (based on 1,000 lbs. = 454 kg. of body weight) at rest (neither working, nor reproducing, nor gaining weight) needs about 14.5 Mcal. of digestible energy per day, that is usually provided with good forage. This requirement, however, may have variations according to individual needs. “Easy keepers,” for instance, are horses that tend to obesity; they can be provided with less energy than this in their diet due to their particular metabolism, ideally not from cereals or concentrate feed containing cereals and/or molasses. Conversely, other horses need a greater amount/quality of feed to guarantee higher levels of energy in order to help them maintain a proper body condition. The key here is keeping records of the diet being offered to each horse (feed sources, amounts, and frequency) and monitoring their body condition to make adjustments as needed.
Young, growing horses (yearlings) need about 25% more energy in the diet than adult horses at rest. Those 18 Mcal. of digestible energy required daily can be supplied with good quality forage (that may include legume) supplemented with concentrate. Lactating mares, and moderately to highly exercised horses require about 75% more energy in the diet than adult horses at rest (≈ 25 Mcal. of digestible energy daily). Horses under high-intense work increase the energy requirements to up to twice of what adult horses at rest need (≈ 29 Mcal. of digestible energy daily). To fulfill these higher needs of energy in the diet, more feed intake (dry matter) should be guaranteed from more caloric feed sources (that may include added fat).
For a horse of any age to gain weight requires a diet with a greater amount of energy than is required for a well-conditioned horse of the same physiological stage. The greater the energy being provided in the diet, the faster the weight gained. However, an excess of cereals (which are rich in energy) or concentrate feed containing cereals must be avoided to prevent laminitis.
Because the energy required by some horses is not always supplied by forage, grains/concentrates are excellent sources for these needs when offered up to 50% of the entire diet (only under supervised conditions). Fat is another source of energy for lactating mares and highly exercised horses. Adding fat increases calories in the diet; therefore, feeding grains/concentrates can be reduced.
When horses being trained/exercised regularly become difficult (“hot”), the energy supplemented from carbohydrates (sugars and starch) should be reduced/eliminated for some days. Once the horse starts behaving, carbohydrates may gradually be increased. An alternate option is using food sources of ‘calm’ energy such as fat and/or low-starch and no molasses concentrate feed.
Notes: The “Percentage of Total Digestible Nutrients” (% TDN) is another way to describe the energy content in horse feed sources. If the total digestible nutrients (TDN) is used to calculate a horse’s diet, the following conversion from digestible energy (DE) may be used:
1 kg. of TDN = 4.4 Megacalories of DE = 4,400 kilocalories of DE.
- Protein is not highly required by horses, compared to other species. An adult horse at rest needs about 9% of crude protein in its diet. Protein requirements are greater for mares during the last three months of pregnancy (10.5% due to the fetal development), lactating mares (no less than 12% because milk produced contains a great amount of protein), and growing horses (about 12% to 14% for growth and development). Additionally, the amount of the amino acid, lysine, is extremely important in the diet of young, growing horses (about 0.55%, equivalent to approximately 35 g.).
Good quality grass hay generally provides the protein required by adult horses at rest. Grass hay mixed with legume hay supplemented with a concentrate containing 12% to 14% protein will fulfill the higher amount of protein required by pregnant mares in the last trimester of pregnancy, lactating mares, and growing horses.
- Fiber, meaning the cellulose and hemicellulose (the structural carbohydrates of plants), is a particularly important part in a horse’s diet that serves two paramount functions in the gastrointestinal tract: Fiber is fermented in the horse’s large intestine (cecum and ventral colon) by specialized microorganisms that live there, from which the final product is volatile fatty acids. Once the fatty acids are absorbed on site, the horse uses them as the primary source of energy. This is what makes a horse an herbivore, grazer.
The second function is to aid the passage of the foodstuff through the gastrointestinal tract. Without it, the peristaltic waves starting at the small intestine, will have trouble moving the foodstuff toward the end to continue its digestion and to eliminate the non-usable material. For these two reasons, a diet for adult horses should contain 25% of fiber in average; in diets for young horses under 18 months it may be as low as 20%. Moreover, lower and higher levels of fiber in a horse’s diet usually lead to gastrointestinal disorders including constipation, colic, and as a consequence, possibly laminitis.
- Horses of all ages should have free access to sodium chloride (salt), found in iodized salt, sea salt, salt bricks/blocks, mineral salt, and mineral salt bricks/blocks. Ideally, the horse should not be forced to eat salt added to the grain/concentrate by human choice.
Other minerals are important for all horses, but especially for stallions during the breeding season, pregnant mares, young, growing horses, horses working moderately and intensely, and lactating mares. For example, the needs for absorbable calcium for horses in these physiological stages range from 20 to 40 g. per day.
Note: Read here 25 Recommendations for a successful horse’s feeding program.