Developmental consequences of diet and activity.

The effect of a protein-deficient and a protein-surfeit diet and continuous access to an activity wheel on food intake, growth, and body temperatures of behaviorally thermoregulating White Leghorn chicks was assessed in two experiments. In Experiment 1, both imbalanced-protein diets depressed intake and growth and differentially affected activity relative to a control diet, but activity did not ameliorate the deleterious effect of a high-protein diet on growth. Diet groups with continuous access to a running wheel did not differ on any measure from corresponding inactive dietary control groups. In Experiment 2, these results were replicated in a lower ambient temperature, and an effect of diet on body temperature emerged. Diets that affected spontaneous activity or body temperature also affected death feigning, a predation defense behavior. The data from behaviorally thermoregulating chicks are consistent with previous findings that activity does not depress growth rate in animals who cannot convert a portion of their intake into adipose tissue.