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Accueil du site → Doctorat → États-Unis → 1989 → Selenium deficiency of sheep in Morocco : Assessment, occurrence and prevention

University of Minnesota (1989)

Selenium deficiency of sheep in Morocco : Assessment, occurrence and prevention

Hamliri, Ahmed

Titre : Selenium deficiency of sheep in Morocco : Assessment, occurrence and prevention

Auteur : Hamliri, Ahmed

Université de soutenance : University of Minnesota

Grade : Doctor of Philosophy (PhD) 1989

To assess the selenium (Se) status of sheep in the major raising areas of Morocco, whole blood Se concentration, erythrocyte glutathione peroxidase (GSH-Px) activity and feed Se levels were determined. A total of 843 blood samples from sheep and 118 feed samples were analyzed. Results showed that 73% of sheep sampled had blood Se concentrations below 100 ng/ml, and were deficient or marginal. Erythrocyte GSH-Px activity was below 19 IU/g hemoglobin and feed Se levels below 0.1 ppm. The enzyme activity was highly correlated with blood Se concentrations (r = 0.9, P $<$ 0.001) in deficient and marginal areas, indicating that GSH-Px can be used as a rapid indicator of Se status of sheep grazing deficient or marginal areas. An experimental study was conducted to test the hypothesis that lambs born to Se-deficient ewes develop the myopathy in utero. Based on muscle damage indicators (Creatine kinase and Lactate dehydrogenase) and whole blood Se concentration, it was shown that at two weeks prepartum, hysterectomy-derived fetuses from Se-deficient ewes exhibited evidence of Se deficiency as indicated by elevated plasma creatine kinase and lactate dehydrogenase activities and a low blood Se concentration. At three weeks prepartum, fetuses from Se-deficient ewes had no biochemical evidence of Se deficiency. The final aspect of this study evaluates various methods of providing Se. Two methods involved the treatment of pregnant and lactating ewes to provide lambs with Se in utero or via the ewe’s milk. A third method involved a direct treatment to newborn lambs. It was shown that a single intramuscular injection of 0.056 mg of Se alone or in combination with vitamin E per kg of body weight one month prepartum prevented Se deficiency in newborn lambs. Whereas, the postpartum ewe and/or newborn lamb Se treatments did not prevent Se deficiency in all newborn lambs.

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