Arginine: An Essential Amino Acid for the Cat

Abstract

The essentiality of arginine for the near-adult cat was demonstrated in three preliminary and two main experiments. In the pre liminary experiments, changing cats (body weights all in excess of 1.6 kg) from a purified diet containing a complete amino acid mixture (basal) to a similar isonitrogenous diet without arginine ( —Arg) caused rapid loss of body weight ( mean ±SE93.3 ±6.8 g in the first 24 hours ), emesis, and inappetance. In the main experiments the mean ±SE body weight of the cats was 2.6 ±0.4 kg. When eight of these cats were given the —Argdiet after an overnight fast, they all exhibited emesis, had tetanic spasms, and one died. Other symptoms included hypersalivation, depression which in some cases was followed by hyperesthesia, hyperactivity, ataxia, and dyspnea. The plasma of these cats showed hyperammonemia and hyperglycemia indicating that the clinical condition was caused by acute ammonia intoxi cation. The eight cats given the comparable diet with arginine showed no ill effects. Five cats given the basal diet with ornithine replacing arginine on an equimolar basis showed neither an increase in plasma ammonia nor glucose concentrations. Cats given the —Argdiet had extremely low 120 minute post-prandial levels of plasma free arginine (less than one-quarter of the prefceding level ). It was concluded that the cat lacks the ability to synthesize ornithine. The consequence of this metabolic deficiency in the cat is that arginine is an essential nutrient: it provides a unique example of a nutrient so critical that one meal without dietary arginine may result in death. The —Argdiet supported growth in young rats, albeit at a slower rate than rats fed the basal diet. J. Nutr. 108: 1944-1953, 1978. INDEXING