ALLOMETRY OF FASTING URINARY NITROGEN LOSS AND BASAL METABOLIC-RATE IN HOMEOTHERMS

This paper presents a review of the use of allometric techniques and d escribes the possible theoretical basis for the allometry of BMR (Basa l Metabolic Rate) and FUNL (Fasting Urinary Nitrogen Loss). Using the technique of allometry, it presents strong evidence of a relationship between metabolic body size W-0.75 with BMR, ONL (Obligatory Nitrogen Loss) and FUNL. It also shows convincingly a casual link between these three parameters. The mean interspecific equations calculated were: F UNL(mg/day) = 418W(0.75); ONL(mg/day) 272W(0.75); BMR(kcal/day) = 71W( 0.75). The allometric ratios were: FUNL/BMR = 5.9mgN/kcal; FUNL/ONL = 1.54; ONL/BMR = 3.8mgN/kcal; ONL/FUNL = 0.65. The allometric relations hip between FUNL:BMR (of 6mgN/kcal) indicates that roughly 15% of prot ein energy is lost during fasting in animals ranging from a mouse to a steer. Moreover, the allometric relationship between FUNL:ONL suggest s that FUNL may be used to estimate ONL and hence protein requirements across a wide range of animals. (C) 1998 Elsevier Science Inc.