Body composition and reproduction in broiler breeders: impact of feeding strategies

ABSTRACT Key words: broiler breeder, feeding strategies, body composition, reproduction, behavior Nowadays, welfare issues in broiler breeders associated with nutrition and reproductive characteristics, are becoming increasingly challenging. Due to genetic selection on broilers, body composition of breeders has changed dramatically during the last 50 years to less fat and more breast muscle. It is postulated that a certain amount of body fat in broiler breeders at the onset of lay is necessary for maximum performance and offspring quality. Body composition of breeders can be influenced by different feed allowances during rearing and lay, as well as by changes in nutrient composition of the diet. However, little is known about the effects of body composition on reproduction of broiler breeders. In this thesis, we investigated the effects of different feeding strategies during the rearing period on body composition at the end of rearing. Moreover, the effects of differences in body composition at the end of rearing, and feeding strategies during lay were evaluated on breeder performance, incubation traits, offspring performance, behavior and feather cover. From this study, it can be concluded that feeding a low protein diet during rearing decreased breast muscle and increased abdominal fat pad, whereas providing an increased feeding schedule, which resulted in a high growth pattern, only increased abdominal fat pad, at the end of rearing. The higher abdominal fat pad content resulted in an increased hatchability during the first phase of lay and a larger number of eggs during the second phase of lay. For maintaining growth pattern, broiler breeders had to provide a higher amount of feed with an increased energy to protein ratio compared to broiler breeders that were fed a diet with a standard energy to protein ratio. This resulted in an increased eating time and less stereotypic object pecking, which may indicate a reduced hunger and frustration. On the other hand, a low daily protein intake during the rearing and first phase of lay can lead to a poor feather cover. Feeding a high-energy diet during the second phase of lay resulted in increased hatchability, decreased embryonic mortality and more first grade chicks.