EFFECT OF EGGSHELL CONDUCTANCE CONSTANT ON EMBRYONIC INTESTINE FUNCTION, HATCHING CHARACTERS AND SUBSEQUENT GROWTH FOR DEVELOPED CHICKENS AND ITS RELATION WITH 2- FLOCK AGE

The present experiment was carried out for studying the effect of eggshell conductance constant (K) on embryonic intestinal function, hatching success, some physiological parameters and post-hatch growth for two flock ages (39-42 vs. 59-62 wks) of Gimmizah breed. The obtained results are summarized as follows: Gimmizah older chickens had higher significant records with respect to pore number and radius of eggshell, egg weight loss % during setting phase of incubation, hatch time and eggshell conductance either in dessicator or incubator and conductance constant and thinner eggshell thickness compared to younger ones. Embryonic mortality was significantly increased for eggs produced from older flock age. Whereas, hatchability percentage, yolk free chick body weight, relative intestinal weight, lengths of duodenum, jejunum and ileum and jejunum maltase enzyme value, relative heart weights besides glycogen values were significantly increased for younger flock age. Triiodothyronine and corticosterone hormones and some hematological parameters i.e. RBCs, Hb and PCV% were decreased (P≤0.05) for embryos and hatched chicks for older flock age. The results proved that younger flock age had a positive effect on eggshell conductance and conductance K which played a cardial role on hatching process, intestinal function, chick body weight and post-hatch growth. Therefore, it is hoping that using the dessicator for determining the eggshell conductance before incubation is useful tool for selecting the suitable senario of incubation condition including temperature and relative humidity to realize the best results of hatching out-put and growth of hatched chicks.