The ratio of protein to energy is also important. Currently, about 50-55 grams of crude protein per megacalorie of digestible energy is needed for sucklings and weanlings. As horses mature, this ratio decreases. Mature, maintenance horses need only 40 grams of crude protein per megacalorie of digestible energy. First, it is costly.
Protein is usually the most expensive feed ingredient.
Secondly, there is the risk of an improper protein to calorie ratio. In young horses, this can lead to decreased feed intake and reduced growth. Another concern is the body's need to get rid of the nitrogen from protein, resulting in greater water intake and excretion of urea. An ammonia smell may be noticed in poorly ventilated stables when too much protein is fed. Young foals are susceptible to ammonia, which can cause pneumonia.