Warmbloods: Same Feeding Plan as Other Horses?

Over the last few decades, European warmbloods and warmblood crosses have become prominent as sport horses in the United States where they compete regularly in dressage, show jumping, and three-day eventing. They also are used extensively as show hunters. The most popular breeds are Hanoverian, Holsteiner, Trakehner, Oldenburg, Selle Francais, Dutch Warmblood, Swedish Warmblood, and Irish crossbreds. From a conformation standpoint, warmbloods possess more substance than light breeds such as Thoroughbreds and Arabians, with heavier bone and muscling and deeper barrels. The current preference among American warmblood enthusiasts is for lighter and taller horses that have greater speed and agility. In addition to their athleticism, warmbloods are well regarded for their tractable dispositions and willingness to work. Feeding well-balanced rations and attending to nutrition-related idiosyncrasies of warmbloods are the first steps in producing and maintaining sound athletes. The primary nutritional goal of managing young warmbloods should be ensuring slow, steady growth and reducing the risk of developmental orthopedic disease.

Immature warmbloods are particularly prone to wobbler syndrome and angular limb deformities such as osteochondritis dissecans (OCD), a growth-related condition characterized by failure of cartilage to mature normally. Improper cartilage development compromises joint function and can lead to lameness and joint effusion of varying significance. In a recent study involving 83 German breeding farms, 226 of 629 Hanoverian foals between five and ten months of age showed OCD lesions on radiographic examination. The defects were detected in the knee, hock, or fetlock joints, or were found in multiple sites. Sex of foal, birth month, level of nutrient intake, body weight, and wither height did not influence the occurrence of OCD. Interestingly, OCD lesions in the fetlock joint were associated with lower body weight, whereas lesions in the knee and hock were linked to higher body weight.

Although it is impossible to ignore the genetic susceptibility to OCD that foals of certain bloodlines possess, weanling warmbloods should not be allowed to become overweight. Occasionally, their growth rate must be restricted.

Overfeeding common concentrates, which are usually abundant in sugar and starch, is known to cause OCD in Thoroughbred foals. In a study conducted by Kentucky Equine Research that included 218 Thoroughbred weanlings, high glucose and insulin responses to a concentrate meal were associated with an increased incidence of OCD. Scientists theorize that excessive insulin may alter the balance of hormones necessary for proper cartilage maturation. The same is thought to be true for warmbloods. As a solution, low-glycemic feeds have been introduced into the marketplace. Instead of supplying calories to young warmbloods in the form of sugar and starch, low-glycemic feeds furnish energy through fat and fiber. Fiber sources such as beet pulp and soy hulls are often used in these feeds. These fibers contain approximately twice the energy of normal fibrous feeds such as pasture and hay.

Some young warmbloods do not require concentrates to maintain proper body condition, especially if access to high-quality hay and pasture is available. These horses should be offered a balancing pellet to ensure proper intake of protein, vitamins, and minerals. Insufficient intake of certain minerals such as calcium, phosphorus, copper, and zinc has been implicated as a cause of OCD.

One trend among owners of warmbloods is to limit the amount of protein given to their charges. In the late 1970s, excessive protein in the diet of young horses was believed to be a cause of developmental orthopedic disease. Subsequent research, however, has revealed no relationship between high-protein rations and onset of developmental orthopedic disease. Weanlings fed protein-deficient rations (less than 12%) had reduced growth rates, but did not have improved bone mineralization relative to weanlings fed diets higher in protein and energy.

Unfortunately, some breeders have not embraced current research. In the aforementioned study of Hanoverians, for example, researchers documented the nutrient content of the diets fed to the foals and their dams. The typical diets of hay and silage failed to meet minimal protein requirements of mares and foals. The refusal to feed appropriate levels of protein has surfaced in the warmblood breeding community stateside, based largely on the vague reasoning that the youngsters “cannot handle the protein.” In reality, the foals were likely overfed starch-rich grain, which inevitably led to behavioral problems such as excitability and growth-related problems such as OCD. Protein intake should not be less than 14% during the first year of life.

Warmbloods mature more slowly than Thoroughbreds and other light horse breeds. A two-year-old warmblood looks much like a gawky, leggy yearling Thoroughbred. Dramatic differences in the appearance of warmbloods from the ages of three to five years are often noted; the horses seem to grow into themselves during these years. Because of this slow maturation, German breeders frequently do not place horses in ridden work until they are four to five years old.

A fraction of warmblood enthusiasts realize the problems associated with accelerated growth but use unconventional methods to slow development. In an attempt to decelerate growth, a handful of breeders choose to curtail the amount of free exercise given to sucklings and weanlings, often keeping them confined to stalls or small run-in sheds. Confinement does not slow growth and increases the chances of developmental orthopedic diseases.

Rather, this management technique is likely to induce obesity and poor bone development. Exercise forces bone to respond and remodel so it becomes capable of withstanding ordinary skeletal stress. In a study conducted at MichiganStateUniversity, researchers found that housing yearling and two-year old horses in stalls without free or forced exercise impaired normal bone growth. This, in turn, may jeopardize soundness.

A chief concern of managing adult warmbloods is keeping them at optimal body weight. Mature warmbloods often are easy keepers, and without proper care they tend to become overweight. An easy keeper is a horse or pony that requires fewer calories to maintain body condition than the average horse of similar age, size, and workload. As with most other horses, warmbloods should be fed a diet consisting largely of forage such as pasture or hay. If horses perform moderate to extensive amounts of work, they will likely need a fortified concentrate to satisfy energy demands. Strict attention should be paid to the manufacturer’s instructions, though. If recommended amounts of the feed are not given daily, the horses may not consume sufficient levels of vitamins and minerals.

Some warmbloods, regardless of their workload, may not require any concentrate. If this is the case, they should be fed a vitamin and mineral supplement.

Warmbloods pose few nutritional challenges to their owners. Important considerations include carefully regulating growth in young horses and maintaining moderate body condition in adults.