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1. Fourteen-week-old intact and castrated cockerels (White Leghorn) were injected intramuscularly with zinc (100 micrograms/kg body weight) as zinc ammonium sulphate solution once daily for 4 weeks and the effects on testes, pituitary and adrenal glands investigated histologically. 2. In intact cocks zinc decreased testes weight significantly, inhibited spermatogenesis and disturbed testicular hormone production. There was an increase in pituitary gonadotrophic cell activity, perhaps an indication of feed-back response to low concentration of testicular hormone. Cortical and medullary cells of the adrenal glands showed signs of activation. 3. No discernible effects of zinc injection on pituitary and adrenal cells of castrates were observed. This may reflect a decrease in pituitary and adrenal responsiveness to repeated stimulation with zinc. 4. The results indicate that the effectiveness of a given dose of zinc was dependent on the physiological condition of the cockerels and the effective site of zinc action was centred in the testes.

The objective of this present study is Studying the effect of crossing and reciprocal cross on productive performance, Fertility and hatchability for local chicken. The experiment was carried out in the farm of the Faculty of Agriculture - Ain Shams University. Their experimental research began when birds from two local breeds 22 week of age, where, sixty chickens (30 Fayoumi breeds, 30 Sinai breeds).were used at 26 weeks of age semen was collected artificially from 12 cocks (6 Fayoumi, 6 Sinai).semen from each cock artificially inseminated 48 female within each breed. Were attribution taken to be a parent stock. They were housed in batteries and then they transferred into individual batteries until the end of the experiment (36 weeks of age). The two breeds were mated and four crosses were produced Male Fayoumi Female Fayoumi (FF), Male Fayoumi Female Sinai (FS), Male Sinai Female Sinai(SS), Male Sinai Female Fayoumi (SF) After the second generation hatching, the resolutely indicated that (FF) breed had the highest Fertility percent while the (SF)cross was the highest Hatchability calculated from the total eggs and also from fertile eggs . and Individual body weight (in grams) was recorded for each sex separately within each breed at 0, 1, 2, 3, 4, 5, 6, 7, 8 weeks of age. Male Sinai Female Fayoumi (SF) was found to be the best breeds in terms of body weight and vitality and better in food conversion. The most important results observed from this study indicated that the (SF) cross had the best in fertility, the best hatchability calculated from total and fertile eggs, body weight and body weight gain. So, it could be concluded that, cross procedure could be used in order to achieve genetic improvement from local breeds, which mean the possibility of increasing our production and hence on consumption from our local breeds and reducing on dependence from foreign breeds. [ABSTRACT FROM AUTHOR]