Two studies were conducted to evaluate 1) the minimum requirement for dietary Phe and 2) the effects of Phe on gastric emptying (GE) and food intake in adult cats. In study 1, the minimum Phe requirement was estimated using the direct amino acid oxidation (DAAO) technique. Four cats were used and received all diets in random order in a Latin rectangle design (0.29%, 0.34%, 0.39%, 0.44%, 0.54%, 0.64%, 0.74%, and 0.84% Phe in the diet on a dry matter [DM] basis). The minimum Phe requirement, in the presence of excess of Tyr, for adult cats was estimated to be 0.59% DM on an energy density of 4,200 kcal of metabolizable energy/kg DM calculated using the modified Atwater factors; higher than current recommendations set in place by the National Research Council and the American Association of Feed Control Officials. In study 2, we first validated the use of the 13C-octanoic acid breath test (13C-OABT) in cats. Then, the effects of an oral bolus of Phe on food intake, GE, and macronutrient metabolism were evaluated. Phe supplementation did not influence food intake, macronutrient metabolism, or total GE, but tended to delay the time to peak GE.

Read the full article in the Journal of Animal Science.