to transform B-carotene to vitamin A and therefore explicitly require active forms of vitamin A which are only found in animal products. This difference in metabolism is due to very low levels of activity of the enzyme B-carotene 15, 15' dioxygenase in feline species. The nutrient profiles developed by AAFCO currently advise a minimum of 3332 IU/kg of vitamin A on a dry matter basis included in adult diets and 6668 IU/kg in the diets of raising kittens as well as pregnant or lactating female cats. Common ingredients which help to incorporate the proper levels of vitamin A into feline diets include various types of liver as well as fish oils. B vitamins Niacin (B3) Niacin is an essential vitamin for the cat; dietary deficiency can lead to anorexia, weight loss and an increase in body temperature. Biosynthesis of niacin occurs by metabolism of tryptophan via the kynurenine pathway to quinolinic acid, the niacin precursor. However, cats have a high activity of picolinic acid carboxylase, which converts one of the intermediates to picolinic acid instead of quinolinic acid. As a result, niacin can become deficient and require supplementation. Biotin (B7) Biotin can be provided in feline diets by adding cooked eggs, liver, milk, legumes or nuts. Microorganisms living in the gastrointestinal tracts of cats are also able to synthesize and supply an alternative source of biotin if proper nutritional requirements are met. Its main function in metabolism is as a coenzyme for essential carboxylation reactions throughout the body; however it has also been shown to aid in the management of certain skin diseases in cats. Biotin is recommended by AAFCO to be included in feline diets at a minimum level of 0.07 mg/kg on a dry matter basis throughout all stages of development. It is required only when the cat is taking antimicrobials that kill gut bacteria. Vitamin C Vitamin C (ascorbic acid) is a water-soluble antioxidant and a free radical scavenger where it will donate an electron to compounds with unpaired elections or reactive but not radical compounds. Supplements of Vitamin C reduce oxidative DNA damage in cats prone to kidney injury, and can be beneficial to add into diets for cats with renal diseases. Vitamin C is not essential for cats and it is not required by the Association of American Feed Control Officials (AAFCO); however, it is commonly added into pet foods as an antioxidant. Ascorbic acid