EFFECT OF URINARY NITROGENOUS COMPOUNDS ON THE ENERGY METABOLISM OF BIRD

In order to study the relationships between the contents of urinary nitrogenous compounds and energy utilization of bird, the sum of nitrogen contents of uric acid, ammonia, creatine and urea voided in excreta was estimated as the urinary nitrogen (UN) in 13-33 day-old fed or fasted White Leghorn male chicks. Energy retention and heat production of birds were determined by comparative slaughter studies. 2.75 mg of endogenous urinary nitrogen (EUn) and 2.19 mg of uric acid was excreted constantly per kJ heat production in fasted bird. One mg of UN was proportionated to 32.26 J (r = 0.999, n = 8) of the urinary energy (UE) in fed and 32.97 J (r = 0.9998, n = 8) of the endogenous urinary energy (UEn) in the fasted bird. Also relationships between 1 mg of uric acid and 38.95 J of UE (r = 0.998, n = 8) or 38.97 J of UEe (r = 0.996, n = 8) were significant (p<0.01). The EUn (r = 0.997, n = 4), uric acid (r = 0.995, n = 4) and metabolic fecal energy (FEm) plus UEe (r = 0.961, n = 4) were increased with the increase of body weight (g/bird). Metabolic fecal nitrogen (MFn) or energy (FEm), EUn and UEe per unit diet were not influenced by the age of day or body weight. The results indicated that energy and protein utilization of bird can be approximated by the relationships among urinary nitrogen, urinary energy, uric acid content in excreta and body weight of bird.