Abstract

The vegetation eaten by animals on large areas of several continents is deficient in phosphate and deleterious effects on physiology, particularly reproduction, ensue. Records on bone chewing behaviour by both pastoral andwild game animals extend over two centuries. In laboratory investigation of this apt behaviour it has been shown that the appetite for bones is innate and specific and cued predominantly by olfactory stimuli. It is suppressed by rapidly increasing the plasma phosphate concentration to normal but not influenced by increasing the phosphate concentration in cerebrospinal fluid. The central organization of this genetically programmed behaviour appears to differ from systems subserving thirst and sodium appetite.