Horse owners and trainers competing in today’s performance horse industry must be aware of all factors which affect ultimate performance in the arena or on the track. Nutrition and feeding of the foal prior to and after weaning is often a neglected area of care and attention. If we are to expect optimum performance later in their life, nutrition of the young horse from birth to two years of age must be managed with careful consideration to future soundness and longevity.

Young horses are potential future athletes. Proper skeletal development is of utmost importance. One of the major problems in the horse industry is injuries and unsoundness in young performance prospects. Developmental orthopedic disease (DOD) is an issue in all segments of the performance horse industry and is likely related to the high incidence of injury and skeletal failure in young working horses. Many of our high-profile events in both racing and show horses involve immature horses which are less than 3 or 4 years of age. It is imperative that we assure that these young horses get the very best nutritional balance during their early developmental stages.

Proper balance of protein and calories is one of the keys to optimal growth. Growing horses require high quality protein, which means a balance of required amino acids. Specific amino acids are required by the young animal for protein synthesis and proper growth of muscle and skeletal tissue. Assuring adequate lysine intake is important for growth. However, the total balance of all the required amino acids is critical and other amino acids such as threonine and likely, methionine and cysteine also effect growth and development of the skeletal system. What this means is having a high-quality protein source in the diet is of utmost importance. For the weanling up to 1 year of age, when feeding grass hay, a diet containing at 16 to 18% crude protein from high quality sources is recommended.

The other side of the equation, caloric intake is the other key to proper development, while reducing the incidence of DOD. It is important to assure adequate skeletal growth without creating excess body weight or fat deposition. This is the reason diets for growing horses are formulated based on nutrient to calorie ratios. It is recommended that protein requirements are slightly above actual needs while keeping energy intake to a minimum level. The age-old practice of feeding straight oats and hay to young horses demonstrates the importance keeping the nutrient-to-calorie ratio in check. Research has shown that young horses on this type of feeding program will get fat, but will suffer from inadequate skeletal development. Likewise, producers should be cautious about adding additional fat to an already balanced diet. This scenario may significantly increase the calorie intake without increasing the intake of other nutrients required for rapid growth such as protein, calcium (Ca) and phosphorus (P). Keep in mind that diets which are adequately balanced for a slow or moderate rate of growth, may become a real problem if will fed at levels to attain rapid growth rates. In this case, protein, and mineral balance becomes even more critical to help prevent DOD. Since bone is comprised primarily of protein plus calcium (Ca) and phosphorus (P), the right balance of these minerals in relation to the energy intake is critical. Ca makes up about 34% of the total mineral content of the skeletal system, while P makes up about 17%. Since bone density and strength does not peak until about 5 years of age, it is imperative to make sure young horses have adequate Ca and P intake for the first several years of life. Ratio of Ca to P is also important and that ratio should be between 1.5 – 2.0:1. If Ca levels reach levels which are over a 3:1 ratio, P absorption may be impaired. This is one of the problems often encountered when horses are fed straight alfalfa hay or cubes with no additional P supplementation. Young horses on this type of feeding program are predisposed to skeletal development issues. Young horses should be fed good quality grass hay or a mixture of alfalfa and grass hay to help improve the Ca:P balance. Also, feeding a high- quality concentrate which is specifically formulated for growing horses is a safeguard to assure adequate Ca and P intake.

In addition to Ca and P balance, several trace minerals such as copper, zinc and manganese play essential roles in bone and cartilage development. Not only is adequate intake of these minerals essential, but the balance of one mineral to the others are important as well. Therefore, horse owners should feed a high-quality concentrate which has been formulated for growing horses along with a good quality forage. They should also avoid over supplementation of additional additives that may change this critical balance and lead to DOD issues. Vitamin A and vitamin D both are involved in growth and skeletal development and have minimum requirements for all horses. Over-supplementation of both vitamins also can lead to toxicity issues, so once again, feed a balanced concentrate and do not supplement with other additives unless directed to do so by a qualified nutritionist. Adequate vitamin E in the diet is essential for overall health and immune response, so important for young horse, especially those in high-stress situations such as fitting for show or sales. In summary, total nutrient intake is critical for optimum skeletal development in young horses. Not only is proper development essential for soundness during these formative years, but likely determines longevity and ultimate usefulness of horses later in life. When providing protein and energy intake which promotes maximum growth and development, the nutrient balance of the total diet is even more critical. Mineral intake, including Ca, P and trace minerals, is also critical and can be affected by the forage portion of the diet. Feeding a high quality, properly formulated concentrate with good quality forages, paired with proper exercise programs, will help mitigate developmental problems in young growing horses.

Dennis H. Sigler, Ph.D.
Retired Texas A&M University Extension Horse Specialist
MFM Equine Nutrition Specialist