Metabolic basis for some of the nutritional peculiarities of the cat

Abstract

The nutritional requirements of most mammals exhibit a remarkable degree of similarity, a reflection of common evolutionary origin. However, among mammals two groups, ruminants and carnivores, appear to possess the greatest divergence in dietary requirements. The former group have been extensively studied, their nutritional peculiarities arising from a specialized pregastric digestive system. Carnivores have been largely neglected by nutritionists, and yet offer a most interesting divergence in dietary requirements amongst mammals. It would appear that the specialized diet, i.e. animal tissue, of true carnivores has permitted metabolic adaptation through modification of enzymes and enzyme systems which are expressed as peculiarities in nutritional requirements. The purpose of this paper is to review the metabolic basis for some of the nutritional peculiarities of the domestic cat, a true carnivore which has received the most attention. The following nutrients, or metabolic functions, are discussed: vitamin A, niacin, taurine, arginine, gluconeogenesis, nitrogen conservation and essential fatty acids. The latter two topics are covered by other discussants at this symposium and are only included here for completeness. The reader is requested to consult the relevant papers of Rogers & Morris (1982) and Rivers (1982).

Idiosyncratic nutrient requirements of cats appear to be diet-induced evolutionary adaptations

“…The present overview of the idiosyncratic nutritional requirements of domestic cats updates an earlier review (Morris & Rogers, 1982) and attempts to link the dietary essentiality of these nutrients to differences in the activities of key enzymes. The limited ability of cats to control the aminotransferases and urea cycle enzymes explains the high protein requirement of cats.…”

NORMAL THORACIC AND ABDOMINAL DISTRIBUTION OF 2‐DEOXY‐2‐[18F]FLUORO‐d‐GLUCOSE (18FDG) IN ADULT CATS

“…Cellular distribution of 18 FDG is largely dependent on two factors: presence and activity of various glucose transporter proteins (GLUT 1–12) to allow FDG entrance into the cell, and hexokinase enzyme activity to phosphorylate and thus trap FDG within the cell, preventing its passage through additional steps of glycolysis 2,17,18 . Cats' obligate carnivore status may influence their amount of hepatocellular glucose transporter proteins, as carbohydrates are not a vital dietary nutrient in this species, with the exception of the lactating queen 15,19 . To date, there is minimal information describing glucose transport proteins in normal feline tissues 20,21 .…”

Small Nondomestic Felids in Veterinary Practice

“…16,20,21 Cats are predisposed to vitamin A, niacin, arginine, and taurine deficiencies and have a high requirement for protein relative to other animals. 3,20,22,23 Moreover, they have a reduced ability to convert glucose to glycogen, so excess glucose is stored as fat, and cats fed a highcarbohydrate diet have a tendency to become obese. 15,20 Raw meat is not a requirement in the diet, and commercial diets made for domestic cats or diets formulated for carnivores are adequate for the smaller nondomestic felids and hybrid breeds.…”

“…3,20,22,23 Moreover, they have a reduced ability to convert glucose to glycogen, so excess glucose is stored as fat, and cats fed a highcarbohydrate diet have a tendency to become obese. 15,20 Raw meat is not a requirement in the diet, and commercial diets made for domestic cats or diets formulated for carnivores are adequate for the smaller nondomestic felids and hybrid breeds. 3,10,15 Supplementation with calcium and vitamins is required if an all-muscle meat or organmeat diet is fed.…”