Young horses are considered weanlings from the time they're separated from their mothers until one year of age. This is a critical time in the young horse's life, and nutrition plays an important part. Here are five important points to consider when feeding a weanling:

1. Nutritional Needs: From the time foals are weaned to the time they turn 1, the young horse is considered to be on the highest nutritional plane of its life. Weanlings consume approximately 3% of their body weight in dry matter per day. Key components in the weanling's diet include:

• Energy—Weanlings need energy to support their growth and development. Weanlings that consume too much energy will grow too fast, while too little energy will slow their growth. Both scenarios can put weanlings at risk for developmental orthopedic disorders. Consult a veterinarian or equine nutritionist if questions arise on determining the ideal amount of energy for each weanling. 
• Protein—High-quality protein is essential for muscle, ligament, and tissue development, so ensuring your weanling consumes adequate amounts of protein each day is crucial. The following equation can be used to determine a growing horse's protein requirement: Crude protein (or CP) requirement in grams = (body weight in kilograms x 1.44) + ((average daily gain x 0.2) / E) / 0.79. In the equation, 1.44 stands for the number of grams per kilogram of body weight needed, and E (the efficiency of use of dietary protein) is estimated as 50%, so plug .5 in for that. Most young horses that should mature to around 1,100 pounds will need about 675g of protein per day when they're around 6 months old.
  
  Research has shown that diets low in two essential amino acids, lysine and threonine, will slow growth rate and decrease feed efficiency in young, growing horses. Lysine should account for a just over 4% of the weanlings total protein requirement, and although evidence seems to point to threonine possibly being important for growth, the National Research Council hasn't set a dietary requirement. Still, it's important to ensure weanlings' feed contains a quality source protein, including adequate amounts of lysine and threonine.
• Minerals—Weanlings need an ample supply of minerals, especially those needed for bone development (including calcium, phosphorous, zinc, and copper), are necessary for growth. However, under or over-supplementation must be avoided to prevent developmental orthopedic diseases. It's advisable to work with a veterinarian or equine nutritionist to ensure weanlings' mineral needs are being met. 

2. Treat Each Horse Individually: Regardless of breed or sex, each weanling should be individually monitored and fed according to their needs. Feeding each young horse on an individual basis will not only allow you to keep your feeding costs as low as possible, but also create the best nutritional plan for each animal. 

3. Stress and Decreased Feed Intake: Weaning is an extremely stressful time for young horses. This stress is usually accompanied by a decrease in daily intake of food and slowed growth. Therefore, it is ideal that a high-quality diet, both hay and grain, be provided after weaning. Creep feeding prior to weaning will also help the transition period so that growth and development is not detrimentally affected.

4. Exercise: Research has shown that weanlings benefit from free exercise or turn out. Scientists believe exercise helps to regulate bone and muscle growth, so allow young horses ample turnout opportunities.

5. Record Keeping: To reduce the risk of developmental orthopedic diseases due to rapid fluctuations in growth rate that commonly occur at weaning or during other times of stress, a variety of measurements can be taken from birth. Average daily gain, wither height, and hip height are common measures of growth rates in young horses. By monitoring these on a weekly basis, changes can be made in the diet accordingly to maintain a level plane of growth.

Take Home Message

Weaning is an important time in a young horse's life because of the increased needs for energy, protein, and minerals. Feed each weanling individually to monitor his or her proper growth and development during this critical time, and provide exercise or turnout daily to help regulate growth.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.