Well developed muscles are much more than cosmetic. Efficient, strong muscular function allows smooth movement, athletic balance, speed and endurance.
L-lysine, a common amino acid deficiency limiting muscle development
About 70% of a muscle’s volume is water but water is important for more than bulk. Dehydrated individuals suffer more muscle damage and higher muscle enzyme release after a competition. Exercise causes more oxidative stress when there is dehydration. Dehydration during endurance exercise increases lactate levels and accelerates the depletion of glycogen, the most critical energy source for exercise. It also takes 7 grams of water to replace just 1 gram of glycogen after exercise.
It doesn’t take an obviously dehydrated horse to have these effects. Even mild dehydration has negative consequences in muscle. For maximum performance, recovery and gains from training make sure the horse is optimally hydrated by feeding 30 grams of plain salt every day and carefully replacing salt lost with sweating. The body needs adequate sodium intake to maintain hydration. Allow the horse to drink as much as they want after exercise and during prolonged exercise.
Next to water, protein is the major component of muscle. If the total daily intake of protein is insufficient, muscle bulk will suffer. If the horse’s diet is questionably adequate for protein it should be supplemented with a high quality protein from sources such as soybean, whey, potato or pea. A typical amount would be 100 to 200 grams of a 40% protein product.
More common than inadequate total protein intake is shortage of key essential amino acids. Amino acids are the building blocks of protein. Essential amino acids are those the horse’s body cannot manufacture for itself. The sequence of amino acids in a muscle is dictated by the DNA. If an essential amino acid is next in sequence but is not available, assembly of the protein strand will stop.
It is currently thought that lysine and threonine are the two essential amino acids most likely to be deficient and limiting the ability to build muscle. These can be supplemented in their pure form. Usual amounts are 10 to 20 grams of lysine and 2 to 4 grams of threonine. Deficiency of the amino acid methionine is also possible. This impacts muscle function more than bulk because methionine combines with lysine to form carnitine, a carrier needed for the muscle to burn fat. Supplement 5 to 10 grams/day.
Muscle requires a full spectrum of vitamins and minerals and many deficiencies can influence function. Two of special interest are vitamin E and selenium, both because they are very common deficiencies and because of their role in muscle. Energy generation creates a heavy load of free radicals and antioxidant protection is critical.
A horse not on fresh pasture is getting insufficient vitamin E. E provides antioxidant protection to structural membranes of the cell. Supplement at least 2000 IU/day. Selenium is needed for function of the glutathione defense mechanism that protects the cell’s watery internal environment. Most horses do well on 2 mg of selenium/day, preferably from selenium yeast.
Nutrition is powerful and completely within your control. Use it to support the best muscle size and function possible.
Eleanor Kellon, VMD