الفهرس 
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Abstract
This study was carried out at the poultry farm belongs to the Department of Animal production, Faculty of Agriculture in Qena South Valley University. The study aimed to evaluate the effects of dietary natural sources of vitamin A (yellow carrot, clover and sweet potato) on the productive performance, some metabolic and some immune responses of broiler chicks.
At the start of the experiment, three hundred and thirty one day old Hubbard were obtained. The chicks were divided into 11 treatments, each of 30. Chicks of each treatment were subdivided into 3 replicates each of 10. All replicates were housed in closed poultry house.
The experimental period was divided into two feeding phases (starter: from 0 - 3 weeks of age) and grower (from 4 -6 weeks of age). The basal experimental diets were of 23.07% and 2926.6 Kcal ME/kg, 20.02% crude protein; and were of 3074.8 Kcal ME/kg diet for the starter and the grower diet, respectively. Diet of positive control was as the same as the experimental diet, except replacing yellow corn instead of maize. Drinking water was available all the time during the experiment, and daylight and artificial light were applied to maintain 23 hrs light per day during all the experimental period.
The experiment was included eleven treatments. Treatment 1, chicks were received diet with maize (negative control); in treatment 2, chicks were received yellow corn instead of maize (positive control); in treatments 3,4 and 5 chicks were received diet of maize supplemented with 1%, 2% and 3 % of air dried yellow carrot; in treatment 6, 7, and 8 chicks were received diet with maize supplemented with 1%, 2% and 3% of air dried clover hay; while in treatments 9, 10 and 11 chicks were received diet of maize supplemented with 1%, 2% and 3% of air dried sweet potato, respectively.
Body weight was recorded by replicate at 3 and 6 weeks of age. Feed intake was measured weekly for each replicate and these data were suppressed to each three weeks period. Then feed conversion (feed: gain) was calculated for each replicate within each period.
Obtained results can be summarized as follow:
1. Yellow carrot has more vitamin A then sweet potato and clover hay, respectively.
2. Supplementing the broiler diet with natural sources of vitamin A augment significantly (P<0.05) body weight in both ages than (positive and negative) control treatments.
3. Obtained data show significant increases on feed intake for the chicks received natural sources of vitamin A in their diets.
4. Supplementing the broiler diets with natural sources of vitamin A improve significantly (P<0.05) feed conversion than control. , it is clear that gain: feed ratio improved significantly in a linear manner with an increase in dietary vitamin A.
5. Obtained data reveal that serum total protein, globulin, glucose, total lipids, liver enzymes (GOT and GPT), calcium, total and inorganic phosphorous, vitamin A and thyroid hormones (T3 and T4) were significantly (P<0.05) increased by, supplementing the broiler diet, increasing the amount of natural sources of vitamin A.
6. Obtained data reveal that serum albumin / globulin ratio, triglycerides and cholesterol were significantly (P<0.05) decreased by, supplementing the broiler diet with natural sources of vitamin A.
7. However, serum albumin and organic phosphorous did not significantly changed by supplementing the broiler diet with natural sources of vitamin A in different levels.
8. Obtained data revealed that total count of WBC’s, monocytes%, heterophils%, lymphocytes% and antibodies production were significantly (P<0.05) increased by supplementing the broiler diet with natural sources of vitamin A in different levels.
9. While, values of H/L ratio showed significantly differences among treatment, and significantly (P<0.05) higher values than control.
It could be concluded that, for better broiler performance as well as immune response, yellow carrot or sweet potato might be used with maize, instead of yellow corn.