The present study was carried out to investigate the effect of season on growth performance traits, leptin hormone concentration and gene expression for innate immunity in response to vaccination against pasteurellosis. A Total of 384 weaned rabbits were used in this study. They were from females of APRI line, a local population. Rabbits weaned at 33-35 days and introduced in the experiment at weaning. Arbitrarily, weight at beginning was considered as the "5 weeks" weight. All rabbits were weighed every 7 days and the feed consumption measured at the same weekly interval until all rabbits were 12 weeks old. Leptin hormone level in serum was assayed. Vaccination with Pasteurella multocida was studied in a challenge experiment. Gene expressions for interleukin-6 (IL-6) and toll-like receptor-4 (TR4) were assayed by Real Time-PCR. Parameters of the antioxidant status were included reactive oxygen species, (ROS) expressed as H2O2, Lipid Peroxide, expressed as malondialdehyde and glutathione peroxidase. Blood samples were taken at 8, 10 and 12 weeks of age, respectively. The body weights in winter at W5, W8and W12 of age were higher than those in others seasons. Season had a significant (P≤0.05) influence on daily gain and feed intake. Season had no significant influence on Leptin hormone level in growing rabbits. Vaccination with Pasteurellamultocida led to an increase in gene expression for IL-6 in autumn and winter. Expression for IL-6 in spring has the lowest values. Gene expression of TR4 in rabbits under different seasons was not significantly different. It is can cluded that vaccination by Pasteurellamultocida needs some additives to enhance immunity especially during summer and spring seasons.

The effect of breederʼs strain (Hy-line Brown and Hy-line White W36) flock aged (28, 36, 46, 55, 66 weeks of age) and breeding season on some physiological measurements in egg, demand organs, dead supply organs and lymphoid organs were examined. At each age, 10 unhatched eggs from each genotype were examined on embryo weight percentage, Chorioallotoic  weight %, albumen pH %, yolk pH %, residual yolk %, pectoral  muscles weight %, hatch muscles weight %, heart, liver, lunges, spleen, burse weight percentage. There was a significant difference between layer breeder genotypes for lunges weight percentage the brown was higher (0.84) than the white (0.62). The breeding season had a significant effect on heart, liver, lunges weight percentages in winter higher than summer but yolk pH and residual yolk the summer higher than the winter. Breeder's age significant effect on embryo weight percentage, Chorioallotoic weight %, albumen pH %, yolk pH%, residual yolk %, hatch muscles weight % heart, liver, lunges and burse weight percentage.  It could be observed that the genetic differences among layer breeder strain and age of breeders can affect the hatchery performance. Additionally, handling of hatching eggs and incubation management can play a major role to overcome numerous hatching problems. In turn, increasing the production of table eggs and achieves the balance between supply and demand of that strategic commodity in Egyptian market.