Influence of temperature, dietary energy, nutrient concentration and self-selection feeding on the retention of dietary energy, protein and calcium by sexually-maturing egg-laying pullets.

1. On a daily temperature cycle of 25 to 35 degrees C and during the onset of lay, gross energy in droppings were increased significantly by 3 to 5%. There were no changes in energy metabolisability. Overall, less energy was excreted and energy metabolisability was improved on higher energy diets. 2. Crude protein and calcium losses decreased and their retention efficiencies increased with the onset of lay. Less protein and calcium were lost at the high temperature with corresponding increases in retention. Less protein and more calcium were lost on the higher energy diet. 3. Crude protein excretion was increased and calcium excretion reduced with self-selection feeding. Energy metabolisability and crude protein retention efficiency were reduced by this feeding practice.