A foal’s diet is critical to development, disease prevention, and future performance.

Proper nutrition throughout the foal's first year of life can impact his musculoskeletal health and his future performance as an athlete. The growing foal passes through three important nutritional phases: nursing, creep feeding, and weaning. During nursing, proper feeding of the dam ensures her milk production and quality are adequate for the foal. Creep feeding (feeding foals concentrate separate from mares) then provides nutrients as the mare's milk production begins to wane and minimizes the stress of weaning. Finally, once the foal is weaned, the diet must be formulated to provide all of the nutrients the growing horse needs.

"During the first few years of life, nutrition has a large impact on many body systems," says W. Burton Staniar, MS, PhD, assistant professor of equine science at Pennsylvania State University. "During this time the skeleton is developing at a rate only second to that which occurs in utero. The tissues and organs are adapting to the nutritional environment of the foal. Tissues are all turning over at a great rate and this all means that it is during this time in a horse's life that those feeding the horse can probably have the greatest impact on the future health and athletic performance they will see from their horse."

Staniar stresses that those directly caring for the growing horse should monitor his condition closely and adjust nutrition appropriately.

The Nursing Foal

The foal should begin to nurse within the first couple of hours of life. This will ensure the foal receives adequate colostrum from the mare to provide him with sufficient passive immunity (antibodies transferred from the dam to the foal through the colostrum). Foals will continue to nurse multiple times per day. While some might start nibbling solid feeds within a couple of days of life, the milk produced by the mare (and consumed by the foal) should meet all of the foal's nutritional needs until he reaches approximately two months of age. Thus, adequate nutrition for the nursing foal requires providing adequate nutrition for the lactating mare.

According to Carey Williams, PhD, Rutgers University's equine extension specialist and associate director of extension at the Equine Science Center, "The mare's diet is just as important (as the foal's). The majority of the nutrients in the first few months of life come from (her) milk."

During these first two months of lactation ("early lactation") the mare produces approximately 3 kg of milk per 100 kg (220 pounds) of her body weight per day, although ranges from 2.3-3.8 kg have been reported. During late lactation mares produce approximately 2 kg of milk per 100 kg of body weight. The milk composition also varies with stage of lactation, as milk within the first four weeks of lactation tends to have higher energy, protein, calcium, and phosphorus levels than milk at five to eight weeks or at nine to 21 weeks postpartum. The milk's nutrient concentration and the amount of milk the mare produces affects her nutrient requirements such that in early lactation, when milk production is highest, her nutrient needs are higher, and she should be fed accordingly.

The impact of the mare's nutritional status on milk production and quality is of great interest to researchers and veterinarians. In one study where mares were fed either 80, 100, or 120% of their required energy intakes, there was no difference in foal growth, although the mares lost or gained weight accordingly (Pagan et al, 1984, Journal of Animal Science). If the mare is thin and does not receive adequate nutrition, the quantity of milk she produces tends to decrease. Dietary composition (i.e., roughage to grain ratios, added fat) and energy excess also appear to impact milk composition (milk fat or protein content).

Williams states that, during lactation, mares might be "using more energy to produce milk than they are consuming. In order to keep them from losing weight they need to be fed energy-dense diets." Thus, the mare should be offered good-quality hay (free-choice) and concentrate (fed at approximately 0.5-1.5% of her body weight; more in early lactation, fed to maintain body weight and condition).

"Careful attention should be paid to the nursing behavior of the foal," Staniar emphasizes. "This is an important indicator of the health and general well-being of the foal. During the first few days of life you should see the foal suckling several times an hour. If the dam's udder becomes distended or she is dripping milk, it may be an indicator that the foal is not suckling. This is a situation that should raise the attention of those caring for the foal immediately."

If the foal is not suckling, this could indicate a condition such as dummy foal syndrome; contact your veterinarian right away.

Creep Feeding

If given access, a foal will often start nibbling at his dam's concentrate within a few days of life. Williams advises owners to be careful offering creep feed, as "many people don't realize that foals will eat their mother's feed as well as their own."

Creep feeding isn't as nutritionally important until the foal is around eight weeks old, at which point the mare's milk production and quality start to decrease. At this time, the foal won't be meeting his nutrient requirements through nursing alone, and offering creep feed becomes increasingly important. Furthermore, studies have shown that foals that are offered creep feed have higher average daily weight gains and experience less weaning stress than foals that are not offered creep feed.

Provide creep feed using creep feeders, which allow access for the foal, but not the dam. "I really like the scenario in which foals are given an opportunity to share with their dams or have access to creep feed prior to weaning," says Staniar. "As with any nutritional transition, it is best if they can occur gradually, and creep feeding allows the foal to transition itself to a diet similar to what it will have after weaning." Foals will also start to consume hay and/or pasture as available, although they will consume more concentrate than forage during this time.

Before four months of age, the foal should be offered up to 0.5-1 kg of feed per 100 kg of body weight per day. The concentrate should be formulated especially for the growing horse, although many companies produce feeds for mares that are specifically suitable for creep feeding. Whole grains are not recommended as they tend to be low in calcium and copper, nutrients important to foal growth and health. Creep feed should contain approximately 14-16% crude protein, 0.7-0.9% calcium, 0.5-0.6% phosphorus, 50-90 ppm (parts per million) copper, and 120-240 ppm zinc.

Feeding the Weanling

Once the foal is fully weaned from the mare, he should be provided with free-choice good-quality grass or mixed grass-legume hay and water, and a measured amount of concentrate. Concentrate should be offered at a rate of approximately 1-1.5% of the foal's body weight. Again, the concentrate provided should be formulated for growing horses. It should contain approximately 14-16% crude protein, 0.8% calcium, 0.5% phosphorus, 50-80 ppm copper, and 100-200 ppm zinc.

"The growth rate of weanlings is known to decrease considerably during their first winter," Staniar cautions. "This leads to a subsequent period of rapid compensatory growth in the following spring. If adequate growth is maintained in the first place (via proper nutrition), it should not need to undergo compensatory growth later."

Other Considerations

A key element in managing growing horses' nutrition is to monitor their growth rates. Many feed companies will send a representative to your facility to weigh your foal(s) (ideally with a portable scale), but height measurement is also useful.

There are a few equations available to estimate body weight in foals for those without access to a scale. Some take into consideration heart girth and body length in addition to length and circumference of the forelimb, but a simple equation using a weight tape is: Weight (kg) = Heart girth (meters)3 x 90. Also monitor body condition to ensure your foal isn't becoming too fat or thin (see www.TheHorse.com/pdf/nutrition/bcs-poster.pdf to determine proper body condition score).

The average daily gain for a foal slows as he ages, but it will be approximately 0.84 kg/day for a 4-month-old (for an expected mature weight of 500 kg, or 1,100 pounds), 0.72 kg/day for a 6-month-old, and 0.45 kg/day for a yearling. Staniar and his graduate student, Andrea Graeff, presented data at the American Society of Animal Science meetings in Colorado in July 2010. Their work in Thoroughbreds found that a younger foal might grow about 0.25 cm per day, while a weanling might grow at a slower rate of about 0.05 cm per day. A growing horse that exhibits extensive growth spurts and lags will be more at risk for the development of orthopedic problems (see sidebar).

Another important factor when it comes to the growing horse is exercise. Regardless of nutritional intake, a young growing horse that is provided exercise (even just free exercise in a pasture) develops greater bone strength than a horse confined to his stall. In fact, recent research suggests that differences in exercise allowance impact bone metabolism to a greater degree than do differences in nutrition (Nielsen and Spooner, 2008, Comparative Exercise Physiology). This is not to suggest that nutrition is not important, however. As Staniar advises, "The successful horseman will be the one that develops a management program for (his or her) growing horses that incorporates excellent nutrition with some sort of appropriate exercise program."

Similar to dietary trends for mature horses, more young horse feed products are becoming available in which more of the calories come from sources such as fat and fiber, rather than from starch. Such formulations are designed to minimize glucose and insulin level fluctuations, which might play a role in the development of metabolic or orthopedic disorders. "Providing fiber as an energy source also fits very well with the natural feeding strategy of the horse," says Staniar.

In summary, work closely with your veterinarian and equine nutritionist to ensure that your foal is growing steadily and that you are meeting his nutritional needs.