Written by: Dr. Jacquie Jacob, University of Kentucky
Common vetch (Vicia sativa) is an annual climbing legume that originated in southern Europe but is now grown all over the world. Raw vetch should comprise only 5% to 10% of a poultry diet. Heat treatment significantly increases the levels of inclusion possible. For laying hens, the maximum recommended level of heated common vetch is 25% of the feed.
Overfeeding of common vetch is harmful for two reasons. Vetch contains γ-glutamyl-β-cyanoalanine, which has a negative influence on the metabolism of sulfur amino acids. In addition, vetch contains vicine and convicine, which are responsible for a disease called favism. In poultry, there are undesirable changes in the blood and liver of chickens There is a breakdown of red blood cells leading to anemia. For laying hens vicine appears to alter the structure of the yolk membrane, reducing egg quality as well as fertility and hatchability.