For yearlings, the best food is good pasture grass. It not only provides adequate nutrition, but yearlings turned out to pasture can run, play and strengthen their growing bones. With young horses, your aim should be optimum growth, not maximum growth.
As the University of Minnesota Extension points out, you want your yearling to gain weight at a rate that doesn't tax his developing bones. Feed him too much --especially energy-rich grain -- and he's at risk of developmental orthopedic disorders.
Between his first and second year, the yearling reaches approximately 90 percent of his mature height, but his bone mineral development lags considerably behind, at 75 percent of maturity. If he gains too much weight, his immature bones have difficulty supporting that extra poundage. You want him fit -- not fat.
The risk of orthopedic problems doesn't mean yearlings shouldn't receive grain, only that careful management is essential. You can feed either straight grains, such as oats or barley, or a commercial feed designed for the needs of young equines. If pastures dry up in summer, supplemental grain feeding becomes necessary.
Rather than feeding grain twice daily, as is customary with older horses, feed the yearling his daily ration in several feedings spaced throughout the day.
A yearling needs a diet containing 13 percent crude protein. Good pasture provides that, but if you don't have good grass, you can feed your youngster alfalfa. In addition to alfalfa, your yearling should always have access to good quality grass hay when not on pasture.
If you've had your yearling since he was a weanling, the easiest way to change him from a weanling to yearling diet is to feed him the same amount of grain and/or supplements, but add more good hay when pasture isn't available or of poor quality. That holds true until his second year.
Your yearling may require supplements if pasture is unavailable or poor, or if he is stressed. Horses also need a balanced calcium/phosphorous ratio of 2 to 1. Ask your vet before giving supplements to your yearling. Recommended supplements may include:
- Soybean meal and milk protein, both high in protein.
- Ground limestone or dicalcium phosphate -- added to feed to balance the calcium/phosphorus ratio.
- Vitamin E. This antioxidant particularly helps yearlings stressed by their appearance in the sales or show ring.
- A salt block to replace sodium lost while playing and running.
- Vitamin supplements geared toward young horses.