The effects of hatchery relative air humidity (RAH) and age of breeder hen on incubation yield, on heart weight, on yolk sac and on the ratio of these organs and the newly-hatched chick weight were evaluated. A total of 10,836 eggs of Lohmann LSL of 26, 41 and 56 week-old breeder hens were incubated in three hatchery relative humidity (48, 56 and 64%). Egg weight loss was higher for eggs incubated at lower RAH and for older breeder hens. The hatchability was higher for RAH lower than 56% and lower for eggs of older hens. Higher yolk sac/chick weight ratio was observed for eggs of 41 week-old breeder hens and for eggs incubated at lower RAH (48%).Chicks hatched from eggs of 41 to 56 week-old breeder hens had the highest heart weight/chick weight ratio.
breeder hen; relative air humidity; age of breeder hen; incubation; yield
