الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
6. The present study was carried out at the sheep experimental farm belonging to Animal Nutrition Unit, Department of Applied Radiobiology, Nuclear Research Center, Egyptian Atomic Energy Authority. Inshas, Sharkia Governorate. br Hormonal radioimmunological assay of serum estradiol (E2), estrone (E1), estrone sulphate (E1S) and estrone sulphate (E1S) in fecal samples was performed in the laboratories of the Endocrinology Research Unit, Applied Radiobiology Department, Applied Radioisotope Division, Nuclear Research Center, Atomic Energy Authority. br It was aimed to point out the ovarian estrogens (E1, E2) and estrogen metabolite (E1S) in both serum and fecal samples, as indicator for reproductive activity in hybrid ewes (Ossimi x Rahmani x Barki, with equal genetic proportion), during estrus cycle, pregnancy and post-partum periods. br A total number of 62 ewes were randomly selected according to reproductive farm records and subjected to the study. br Estradiol-17β, Estrone and Estrone sulfate were estimated in blood serum. Estrogen sulfate was estimated in fecal samples, estimations were carried out in the various stages of estrus cycle, pregnancy (every 10 days up to the time of parturition) and Postpartum (every 10 days up to 60 days). br Fecal samples were collected 24 hours after blood collection to reflect the level of serum estrogenic hormones levels in blood circulation. br Results obtained could be summarized as follows: br 1- Estrogens and estrogen metabolites pattern during estrus cycle. br • In ewes showing irregular cycle (silent heat) br Serum level of estradiol-17β was too low to show the typical behavioral character of ewes during heat period. This is the main reason to believe that these ewes are characterized by silent heat. br Serum estrone level showed irregular pattern of variation throughout the period of estimation. br The same pattern of variation was detected in serum estrone sulfate and fecal estrone sulfate, which indicate abnormal metabolic process of estrogen in this case. br • In ewes conceived after one estrus cycle br Serum estradiol-17β level was gradually increased -#102;-#114;-#111;-#109; the first day of estimation to reach its peak at the 15th day then sharply decrease towards the end of estrous cycle. br Serum estrone and estrone sulfate levels showed approximately similar variation pattern as fecal estrone sulfate. This may lead to state that fecal estrone sulfate may be an indicator for regular estrus cycle. br • Ewes showed two successive estrus cycles and conceived after the second estrus. br -#102;-#114;-#111;-#109; the obtained results, it is clearly evident that all estimated parameters (serum estradiol-17β, estrone, estrone sulfate as well as fecal estrone sulfate) had approximately similar variation pattern throughout the various stages of the two successive estrus cycles. This ensures the regularity of estrus throughout the breeding season which is resulted -#102;-#114;-#111;-#109; the optimum coordination throughout hypothalamic-hypophyseal-gonadal axis. br 2- Estrogens and estrogen metabolites pattern during pregnancy br • During the whole pregnancy period br Levels of estradiol-17β and estrone increased as time of pregnancy pass. The rate of increase was relatively higher during the late pregnancy period to reach its maximum level near the 120th day of pregnancy then sharply decreased up to the end of pregnancy period. br The same trend of change was observed in estrone sulfate level, however, the highest level of estrone sulfate was found at approximately the 130th day of pregnancy period. br Similar trend was observed in fecal estrone sulfate content. It increased steadily towards the second trimester and then increased sharply up to the 120th day after which decreased sharply until the 140th day then with lower rate during the last 10 days of the pregnancy period. br • During the first trimester br Results obtained revealed that average of serum estradiol-17β level was fluctuated without distinguished pattern. br The peak value of serum estrone was detected at the 50th days of pregnancy period, while the lowest average was found in pregnant ewes at the 40th day of pregnancy. br On the other hand, average of serum estrone sulfate level increased during the first 10 days of pregnancy then decreased gradually towards the end of the first trimester. br Fecal estrone sulfate increased sharply -#102;-#114;-#111;-#109; the beginning of pregnancy period then decreased up to the 40th day and increased sharply thereafter during the last 10 days of the first trimester period. br • During the second trimester br Serum estradiol-17β level decreased as time of second trimester passed to reach its minimum value at the 80th day -#102;-#114;-#111;-#109; pregnancy period then increased steadily to reach its maximum value at the 100th day. br Similar trend of variation with slight difference was observed in the level of serum estrone along the second trimester. br However, serum estrone sulfate decreased during the period -#102;-#114;-#111;-#109; 60 to 70th day then gradually increased towards the end of the second trimester. br Fecal estrone sulfate level decreased up to the 70th day then gradually increased towards the 100th day to reach an average level of 0.7530 ng/gm at this time. br Highly significant correlations (P-lt;0.01) was found between fecal estrone sulfate and each of serum estrone sulfate (0.82) and serum estradiol-17β (0.78). While, the correlation between fecal estrone sulfate and serum estrone (0.68) was of significant value (P-lt;0.05). This lead to state the possibility to apply fecal estrogenic metabolites estimation for assessment of reproductive activity. br • During the third trimester br Serum estradiol-17β level increased gradually throughout the third trimester -#102;-#114;-#111;-#109; 0.2119 ng/ml at the 110th day to 0.7308 ng/ml at the 150th day of pregnancy period. However, serum estrone level showed no characteristic trend throughout the third trimester period. br On the other hand, serum estrone sulfate level increased up to the 130th day then decreased towards the end of pregnancy period. Fecal estrone sulfate showed approximately the same variation trend as that of serum estrone sulfate. br 3- Estrogens and estrogen metabolites pattern during 60 days postpartum period. br It was obviously clear that all parameters estimated (serum estradiol-17β, estrone, estrone sulfate and fecal estrone sulfate) decreased during the first month (30 days) reaching their minimum values at the 30th day after parturition. br During the second 30 days of the (40-60 day) postpartum period an increase in all parameters estimated (serum levels of estradiol-17β, estrone and estrone sulfate as well as fecal estrone sulfate amount) was observed.