الفهرس 
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Abstract
The experiment was conducted between June to September (2005) to determine the adverse effects of wheat stress on productive, reproductive performance, physiological response and blood traits of laying hens and capability of ascorbic acid, folic acid, chromium and zinc alone or their combination to alleviating the negative effects of heat stress. A total number of 288 laying hens plus 72 cock 28 weeks old, were leg banded and divided into 12 groups of 3 replicates (9 hen + 1 cock) and housed in floor pens. Birds were allotted on the following treatments: 1. Basal diet (without any additives and served as control). 2. Basal diet + 1 mg folic acid (FA)/kg. 3. Basal diet + 250 mg ascorbic acid (AA)/kg. 4. Basal diet + 400 mcg chromium (CrPi)/kg. 5. Basal diet + 100 mg Zn-Meth (Zn-Meth)/kg. 6. Basal diet + mg FA + 250 mg AA/kg. 7. Basal diet + 400 mcg CrPi + 250 mg AA/kg. 8. Basal diet + 100 mg Zn-Meth + 250 mg AA/kg. 9. Basal diet + 1 mg FA + 400 mcg CrPi/kg. 10. Basal diet + 1 mg FA + 100 mg Zn-Meth/kg. 11. Basal diet + 400 mcg CrPi + 100 mg Zn-Meth/kg. 12. Basal diet + 1 mg FA + 250 mg AA + 400 mcg CrPi + 100 mg Zn-Meth/kg. These studies was conduced to estimate the following criteria: • Initial body weight, final body weight, body weight change %, body temperature and respiratory rate. • Egg production traits. Feed intake, egg number, egg weight. • Blood constituents • Blood, yolk and albumen pH • Immune response to SRBC’s • Digestibility coefficient • semen characteristics (volume, motility, life, dead and abnormal %). • Fertility and hatchability and chick hatched weight. In conclusion, results of the present study show that supplementing ascorbic acid, folic acid, chromium and zinc particularly as a combination, improved productive, reproductive, immune response to SRBC’s and decreased glucose cholesterol, MAD in laying hens.