Amino Acid Interaction with Taurine Metabolism in Cats

Abstract

Taurine deficiency represents an important nutritional problem in cats because they cannot synthesize appreciable quantities of taurine, even though substantial taurine is required for biological functions, e.g. bile metabolism and vision^1,2.Although some taurine is synthesized from methionine and cysteine, the main pathway of taurine biosynthesis appears to be limited by low activity of cysteine sulfinic acid decarboxylase. Thus, a dietary source of taurine is considered essential for maintaining normal health in cats, rendering taurine an essential amino acid for this species^3,4.a Feeding cats purified, taurine-free diets depletes plasma taurine to barely detectable levels^5–8. Supplementation with sulfur amino acids failed to improve plasma taurine status substantially (i.e. clinically)^8,9. By contrast, a large intake of dietary cystine (5%) restored plasma and platelet taurine concentrations to approximately 50% of normal, and taurine concentrations in white and red blood cells approximated those in taurine-supplemented cats⁶. However, this high level of dietary cystine caused debilitating neurological symptoms which resulted in death of some cats⁶.