Samenvatting

During incubation, an embryo is developing in the egg for a period of 21 days. During the incubation process air exchange occurs between the egg and its external environment during which it loses humidity due to water diffusion through the shell. This loss in humidity can affect chicks’ quality and, in case of extreme weight loss it increases embryonic mortality and thus may affect hatchability. To emphasize the importance of the before mentioned, hatchability is the biggest economic value for hatcheries. By controlling the egg weight loss factor, hatchery can ensure good quality chick and better hatchability. The objective of this research was to investigate the influence of breeder age flock, breed and hatchery on egg weight loss and hatchability in order to give information as a guide for hatcheries and help them to possibly adapt their incubation profile to breed or age and improve their results. This research has been realized in two hatcheries with two different incubation profiles on breeder flock age ranging from younger than 40 weeks old to older than 60 weeks old and on seven different breeds. The egg weight loss has been measured by weighing all eggs individually before setting and at transfer. Hatchability has been found by counting the difference between the quantity of non-hatched eggs and the total of eggs counted at set for each tray. It has been found that all independent variables such as the hatchery, the breed and the age of breeder flocks have an effect on both egg weight loss and hatchability. Hatchery in Arendonk showed a more beneficial incubation program than Afferden. Furthermore, all results accords that an egg weight loss ranging between 8% and 16% allows a hatchability higher than 80% and that productivity significantly decrease for loss in humidity lower than 8% or higher than 16%. For two breeds out of the seven, egg weight loss lower than 8% and higher than 16% does not affect the hatchability. Also, egg weight loss from hens younger than 40 weeks is mostly distributed between 8% and 12% while the distribution is wider for the hens older than 60 weeks. According to the literature hatchability decreases in hens older than 60 weeks while loss in humidity increases.In conclusion, it is recommended to manage egg weight loss in to order to keep it in a 8% to 16% range. Nevertheless, according to the literature, this range would provide a good hatchability but would not guaranty a good quality of chicks, as long as the recommendations are 11% to 12% of humidity loss to get a healthy chick.