الفهرس 
Chapter I : IntroductionOnly 14 pages are availabe for public view
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Abstract
This study was carried out in the Department of Physiology, Faculty of Veterinary Medicine, (Moshtohor), Benha University during the period from May 2011 to December 2011.The aim of this work was to investigate the effect of leptin in ovo injection into fertilized Japanese quail eggs on the following parameters:1- Hatchability and embryonic mortality percentages.2- Hatching weights.3- Post-hatch growth.4- Feed intake and feed conversion rate.5- Age of puberty and sexual maturity.6- Plasma levels of triiodothyronine (T3), thyroxine (T4), total testosterone and estradiol (E2).This study included 1200 fertilized eggs of Japanese quail artificially incubated at 37.5 oC and 50-60 % relative humidity. On the 5th day of incubation, eggs were randomly divided into four equal groups:group 1: eggs were kept without treatment as a control group.group 2: eggs injected with 50.0 μl normal saline (solvent of leptin).group 3: eggs injected with 50.0 μl of normal saline containing 0.1 μg leptin.group 4: eggs injected with 50.0 μl of normal saline containing 1 μg leptin.Then the eggs were returned into the incubator till hatching occurred.The obtained results revealed that:1- Leptin in ovo injection in Japanese quail didn’t result in significant changes in hatchability and mortality percentages. Hatchability of the control group was 80.13%, normal saline treated group was 80.23%, 0.1 μg leptin /50 μl normal saline treated group was 81.00% and 1μg leptin /50 μl normal saline treated group was 80.23%.2- Embryonic mortality of the control group was 19.87%, normal saline treated group 19.77%, group treated with the lower dose of leptin 19.00% and group treated with the higher dose of leptin19.77%.3- In ovo leptin administration resulted in significant increases in the hatching weights of Japanese quail when compared with control and normal saline treated groups, but there was non-significant difference between the two leptin treated groups. Hatching weight in control group was 7.75g, in normal saline treated group was 7.61g, in group treated with the lower leptin concentration was 9.04g and in group treated with the higher leptin concentration was 9.09g.4- In ovo leptin administration resulted in increases in the live body weights of male Japanese quail during all the experimental period when compared with control and normal saline treated groups, but the significance of these increases differed with leptin concentration and over the different weeks of age. Mean body weight after 8 weeks of age in control group was 234.5g, in normal saline treated group was ..422g, in group treated with the lower leptin concentration was 249.1g and in group treated with the higher leptin concentration was .4024g.5- In ovo leptin administration resulted in increases in the live body weights of female Japanese quail during all the experimental period when compared with control and normal saline treated groups, but the significance of these increases differed with leptin concentration and over the different weeks of age. Mean body weight after 8 weeks of age in control group was .7326g, in normal saline treated group was .652. g, in group treated with the lower leptin concentration was 291.5g and in group treated with the higher leptin concentration was 282.1g.6- In ovo leptin administration resulted in significant increases in the feed intake of treated Japanese quail compared with control and normal saline treated groups.7- At the end of the experimental period, the lowest values of feed conversion rate was in the control group 3250, followed by normal saline treated group 4274, group treated with the lower dose of leptin 6204 then group treated with the higher dose of leptin 62.4.8- In ovo administration of leptin at the lower concentration resulted in significant increases in the testicular weights of male Japanese quail starting from the 5th week of age. The higher leptin concentration caused significant increases starting from the 7th week.9- In ovo leptin administration resulted in significant increases in the ovarian weights of female Japanese quail starting from the 5th week of age. There was non-significant difference between the two leptin treated groups.10- In ovo leptin administration resulted in significant increases in the plasma level of testosterone in male Japanese quail starting from the 4th week of age.11- In ovo leptin administration resulted in significant increases in the plasma level of estrogen in female Japanese quail starting from the 4th week of age.12- In ovo administration of leptin at the lower concentration resulted in significant decreases in the plasma level of triiodothyronine during the 1st, 2nd and 8th weeks of age in comparison to control and normal saline treated groups and a significant increase during the 3rd week in comparison to control group. The higher leptin concentration caused significant decreases during the 1st, 2nd and 8th weeks of age compared with control group and during the 1st, 2nd, 3rd and 8th weeks of age compared with normal saline treated group. Comparing between the two concentrations of leptin solution, the higher concentration caused significant decreases during the 3rd week.13- In ovo administration of leptin at the lower concentration resulted in significant decreases in the plasma level of thyroxine during the 2nd, 4th and 6th weeks of age in comparison to control group. This concentration also caused significant decreases during the 2nd, 4th and 8th weeks in comparison to normal saline treated group. The higher leptin concentration caused significant decreases during the 2nd, 3rd, 4th and 6th weeks of age with control and during the 2nd, 3rd, 4th and 8th weeks with normal saline treated group. Comparing between the two concentrations of leptin solution, the higher concentration caused a significant decrease during the 3rd week.Conclusion:It could be concluded that leptin in ovo injection can be used to increase the productivity of Japanese quail such as its development and growth rate. It also can be used to enhance puberty and sexual maturity.