The generic term vitamin K is now used to describe not a single chemical entity, but a group of quinone compounds that have characteristic anti-hemorrhagic effects and are fat soluble.
Vitamin K antagonists increase the need for this vitamin. Deficiency of this vitamin is produced by ingestion of the antagonist, dicumarol, or by feeding of sulfonamides (in monogastric species) at levels sufficient to inhibit intestinal synthesis of vitamin K. Supplementation of vitamin K will overcome the anticoagulation effect of dicumarol. Mycotoxins are also antagonists that may cause vitamin K deficiency.
Coagulation time of blood is increased when vitamin K is deficient because the vitamin is required for the synthesis of prothrombin.
There are two major natural sources of vitamin K, phylloquinones (vitamin K1) in plant sources and menaquinones (vitamin K2) produced by bacterial flora. Vitamin K derived from bacterial flora would be considered the most important source for ruminants since adequate vitamin K is available even when animals are fed vitamin K-free diets.
Vitamin K is present in fresh dark-green plants. It is abundant in pasture and green roughages, thus providing high quantities of vitamin K to grazing livestock. Swine, poultry and feedlot animals would, however, receive little vitamin K from diets based on grains and oilseed meals.