الفهرس 
INTRODUCTION
VITAMIN A AND ?-CAROTENEOnly 14 pages are availabe for public view
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Abstract
Important infectious diseases in farm animals are thought to be associated with the so-called oxidative stress and free radical release. Tissue defense mechanisms against free-radical damage generally include vitamin A, vitamin C, vitamin E, and β-carotene as the major vitamin antioxidant sources.
In the current study, a total number of 269 sheep of both sexes and different ages were used. The age of these animals ranged from less than 3 months to more than 4 years. These animals reared in small flocks and belonged to some owners at different rural localities in Assiut Governorate.
Of these animals, a total of 207 sheep were proved healthy and chosen to study the influence of some physiological status as age, sex, productive and reproductive status of these animals on the behavior of some blood serum antioxidant vitamins. The remainders (62 sheep) were of both sexes, and their age ranged from 6-12 months. These lambs were suffering from coccidiosis, gastrointestinal nematodes (GIT nematodes), fascioliasis, mange mite, and pneumonia.
Fecal samples and skin scrapping were taken from each sheep for the parasitological examination. Also blood samples were taken from each sheep for estimation of β-carotene, vitamin A, vitamin E and vitamin C levels.
The results showed that the overall mean value of blood serum β-carotene concentrations in young and adult sheep of both sexes and at different productive and reproductive status was 8.099 ± 0.198 μg/dl with a range of 4.23 to 15.64 μg/dl. Also, the overall mean value of blood serum vitamin A concentrations in young and adult sheep of both sexes and at different productive and reproductive status was 32.82 ± 0.84 μg/dl with a range of 15.42 to 85.16 μg/dl. In addition, the over all mean value of blood serum vitamin E
concentrations in young and adult sheep of both sexes and at different productive and reproductive status was 3.77 ± 0.14 μg/dl with a range of 1.2 to 9.04 μg/dl. Furthermore, the results showed that the over all mean value of blood serum vitamin C concentrations in young and adult sheep of both sexes and at different productive and reproductive status was 1.382 ± 0.044 mg/dl with a range of 0.3 to 2.6 mg/dl.
The mean values were decreased (P < 0.05) as the animals advanced in age in both males and females. Sex has insignificant variation (P > 0.05) on the mean values of blood serum β-carotene concentrations.
Both pregnancy and lactation resulted in a highly significant reduction (P < 0.05) in the mean values of blood serum β-carotene than the non-pregnant non-lactating healthy group.
There was significant reduction (P < 0.05) in the mean values of blood serum β-carotene vitamin A, vitamin E and Vitamin C concentrations in sheep infested with coccidiosis, GIT nematodes, fascioliasis, mange and pneumonia when compared with the healthy control group.