May 19 , 2021
Methionine is a major limiting essential amino acid in the horse diet. It is a sulfur-containing amino acid that can be transformed into cysteine, a non-essential amino acid. Soybean meal, canola meal, alfalfa proteins, and animal proteins are major sources of methionine. It is also present in flax, beet pulp, rice bran, sunflower seeds, cereal grains, and grasses.
A derivative amino acid of methionine is cysteine. Cysteine is a non-essential amino acid of horses that makes keratin protein compulsory for proper hoof and hair growth. The sulfur of cysteine bonds with other molecules resulting in strong hooves and hair structure. Methionine is highly recommended in horses for the betterment of skin, hooves, hair health, carbohydrate metabolism, and overall immune function.
Methionine forms s-adenosylmethionine (SAMe), a methyl group donor regulating protein functions and gene expressions. Methionine is also transformed into adenosine, which is an important component of ATP also known as Adenosine Triphosphate, the most significant energy molecule of horses and other living organisms.
Methionine synthesizes taurine, an amino acid that supports the nervous system. It also plays its role in the formation of phosphatidylcholine which is an important phospholipid of the cell membrane. Methionine is also a lipotropic compound that regulates liver function and assists the liver in fat processing. Methionine forms many compounds like coenzyme A, lipid acid, heparin, and glutathione.
The most significant function of methionine is that it donates sulfur and methyl groups to other body compounds for making crucial bio-molecules necessary for the proper functioning of the body. Methionine also produces epinephrine, regulates DNA activity, makes an active form of the folic acid vitamin, detoxifies the liver, and regulates immune responses in horses.
Deficiency of methionine results in deficiency of sulfur which causes weak hooves and rough hair coat along with poor topline. Lack of methionine in diet can result in reproductive disorders in male horses. No harmful consequences in the case of excess methionine are observed till now.
The conclusion is that methionine is an important structural essential amino acid of horses involved in the protein formation of skeletal muscles, antibodies, enzymes, and hemoglobin. So, a horse must be provided with an adequate amount of methionine either by natural diet or by supplementation.