Vitamin K3 has an essential role to play in blood coagulation. Impairment of blood coagulation is the major clinical sign of Vitamin K3 deficiency. In poultry deficiencies in Vitamin K3 can involve small haemorrhages which can appear on the breast, abdominal cavity, wings and legs.  Anaemia and a reduction in bone marrow can result from this blood loss.  In breeding stock a Vitamin K3 deficiency can reduce hatchability of eggs. A Vitamin K3 deficiency in poultry can be related  to low dietary level of the vitamin, low levels in maternal diet, lack of intestinal synthesis. Antimicrobial agents can suppress intestinal synthesis of Vitamin K3 rendering the bird completely dependent on the diet for its supply of this vitamin. Several stress factors ( for example coccidiosis and other intestinal parasitic diseases) increase the requirements of Vitamin K3. Vitamin K is easily destroyed by sunlight and the use of certain drugs, such as antibacterial treatments can counteract the action of the vitamin resulting in deficiency symptoms.