Determination of metabolizable energy requirements and mechanisms of energy mobilization towards lipid egg formation in broiler breeder hens

The changes in performance and body composition of today's broiler breeder pullet and hen and the improvement in efficiency of energy utilization for broilers lead to several questions: What is the daily metabolizable energy (ME) requirement for today's broiler breeder hen at peak production and during the complete 40 week production period? How much dietary energy should be fed to breeder flocks with less uniformity? Do breeders directly utilize dietary energy (carbohydrates, fat, and protein) to produce eggs or do breeders utilize a dynamic metabolic system that consistently provides nutrients to the egg at the expense of body tissue. Do breeders only use dietary energy to replace body tissue changes or is it a mixture of the two systems? Do the systems change as the breeder ages and egg production decreases? The understanding of hen's energy utilization can help with the development of adequate nutritional recommendations, with the advantage of a better knowledge of the functioning of the metabolic machinery that the breeder owns. The objective of the present dissertation is to address these questions by conducting trials that evaluate production performance, energy efficiency, lipid mobilization and nutrient partitioning.