One postulates certain amounts of body fat are necessary at the onset of lay in order to achieve maximal performance. Over the last decades fertility and hatchability declined. A few years ago Dr van Emous and his fellow researchers made an inventory of possible causes for this phenomena. "When fertility and hatchability dropped, we noticed many possible causes, including management, percentage of males, health and behaviour. Apart from these factors, we found in literature indications that a decreased fertility and hatchability could be connected to diet composition, in particular the daily protein intake during the laying period. Besides the decreased fertility and hatchability a substantial fall in production of parent stock at the end of the laying period occurred." Dr van Emous hypothesised this was related to an insufficient fat reserve at the end of rearing. He suspected there was a chance of improvement by changing the diet by lowering the protein intake during the rearing period. As the sector is relatively small, research funding is hard to find and little was known about how body composition affects reproduction of broiler breeders. Plus, because current body composition developed over five to six decades, it was uncertain whether this could be changed or not. Dr van Emous decided to investigate the effects of different feeding strategies on body composition during the rearing and laying period.