Vitamin B12 role in the nervous system and proper brain functioning, homocysteine metabolism, energy metabolism, normal blood functions, cell division, and in the immune system caused this vitamin to be vital as a nutritious supplement in poultry feed. Although the most important function of vitamin B12 is in the metabolism of nucleic acids and proteins, it also functions in carbohydrate and fat metabolism. In growing chickens, a deficiency of vitamin B12 results in reduced weight gain and feed intake, reduced hatchability along with poor feathering and nervous disorders.