Although choline is not a true vitamin in the classical sense, it is an important nutrient as a source of labile methyl groups. It is synthesized by many animal species. Certain physiological states or clinical disorders may result in relative deficiencies and subsequent needs for choline dietary supplements, however. Choline was originally isolated from hog bile.
Dietary requirements for choline have been established for the young of several species including the chicken, pig, rat, and dog. dietary supplements of choline are required to alleviate growth depression and/or hepatic steatitis. Choline-deficient chicks and poults also show a condition called chondrodystrophy (perosis). Chondrodystrophy is characterized by hemorrhaging and flattening of the tibiometatarsal joint, rotation of the metatarsus, and, ultimately, displacement of the Achilles tendon from its chondyles, resulting in crippling. Soybeans contain significant amounts (in excess of 2,500 mg/kg) of choline. Therefore, it has been suggested that the biological availability of choline in this feedstuff may be relatively poor. Molitoris and Baker (1976) reported that choline in soybean meal is only 60 to 75 percent available for supporting chick growth.
