The importance of uric acid as an antioxidant in poultry and the implications on health and productive traits

Birds have high metabolic rates, body temperatures, and plasma glucose concentrations yet physiologically age at a rate slower than comparably sized mammals. The antioxidant activity of uric acid was studied. Study 1 consisted of 18 female broilers consuming inosine or hypoxanthine diets for 7 d while Study 2 consisted of 12 males in a 21 d trial. Study 3 involved 30 mixed sex broilers consuming 40 or 50mg allopurinol per kg BW for 21 d. Plasma uric acid (PUA) and leukocyte oxidative activity (LOA) were determined weekly for all studies and Pectoralis major shear force, relative kidney and liver sizes (RKS and RLS), and plasma glucose concentrations for study 2. In studies 1 and 2, PUA concentration was increased (P < 0.001) in birds fed purines while LOA was decreased (P < 0.05). PUA was decreased (P < 0.001) in allopurinol-fed birds while LOA was increased (P < 0.01). These studies show that PUA is inversely related to LOA.; Urate oxidase is not present in birds yet its product, allantoin, has been measured in birds. Study 4 consisted of 12 male chicks consuming diets supplemented with 0.6 mol. inosine or hypoxanthine per kg diet from 3- to 6-wk-old. Study 5 consisted of 12 toms fed inosine-supplemented diets (0.7 mol/kg) from 6- to 8-wk-old. Plasma allantoin and oxypurines concentrations were measured weekly using HPLC. Allantoin was present in chicken and turkey plasma. The presence of allantoin in avian plasma is evidence of uric acid antioxidant activity.; Previously, dietary fructose raised PUA and improved productive performance in chickens. The effect of dietary fructose on turkeys was studied. Sixty-four, day-old poults were fed diets containing 0 (control), 5, 10 or 15% fructose for 14 weeks. Body weights were measured bi-weekly throughout the study and blood was sampled in wk 8 and 10. PUA, LOA, RLS and differential leukocyte counts were determined. Turkeys fed 10% fructose diet had the highest BW (P < 0.05). Turkeys fed 10 and 15% fructose diets had higher monocyte and lower polymorphonuclear lymphocyte counts (P < 0.05) than those fed control and 5% fructose diets. There were no consistent differences in RLS.