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 present experiment was conducted to evaluate the effect of acidifiers on growth performance and immunity of the African catfish C. gariepinus. This experiment was carried out in the wet lab of Fish Production Branch, Department of Animal Production, Faculty of Agriculture, Ain Shams University. A total of 120 fish were selected as healthy catfish which had a uniform size and average weight of 94.93 ± 0.89 g. A thirty of catfish were used in each treatment divided into three replicates as (10 fish/ quadrate tank). Four experimental diets were formulated at 35 % crude protein with different levels of organic acid blend (OAB); diet was supplemented with 0, 2, 4 and 6 ml of organic acid per kilogram diet. Growth parameters, apparent digestibility of crude protein and ether extract were measured. The chemical proximate analysis for whole-body of fish was conducted at the end of the experimental period. Hematological parameters of fish and liver function enzymes were also measured. The fish group fed on 0.6 % organic acids blend showed the highest significance (P < 0.05) increase in total weight gain (438 ± 14.24 g), specific growth rate, best feed conversion ratio, feed efficiency ratio and highest protein efficiency than the rest of experimental groups. The highest apparent digestibility for crude protein were achieved in the third fish group which fed diet supplemented with acidifiers at 4 ml / kg diet and have significant difference (P < 0.05) with other groups. Data obtained in hepatosomatic index % showed no significant difference among different treatment refers to the health status of liver. However, ALAT  and ASAT recorded high values in the higher group of OAB-treated fish indicating that liver could be affected. Hematological parameters were in normal range except for PCV, Hb, RBCs, and WBCs count which were decreased in the high dose of treated fish. Finally, it could be concluded that using of acidifiers as feed additives at lower doses can enhance growth, productivity and immunity of the African catfish (C. gariepinus).