EFFECT OF VITAMIN E AND SELENIUM ON THE INCIDENCE OF MASTITIS AND RET AINED PLACENTA IN COWS
Dept. of Nutrition and Clinical Nutrition Faculty of veterinary Medicine. Cairo University. Giza. Egypt
Both vitamin E and selenium are dietary essential nutrients both function as antioxidants. Vitamin E is part of the body's intracellular defense against the adverse effects of reactive oxygen and free radicals. This function is closely related to and synergistic with the role of selenium. Selenium as a component of glutathione peroxidase which converts hydrogen peroxide to water and is an important component of the cellular antioxidant system. Deficiencies in either of these nutrients have been related in increased incidence of mastitis and retained fetal membranes. Therefore requirements of such nutrients for optimal reproductive efficiency in modern dairy cattle deserve careful revaluation. The requirements for vitamin E are influenced by the amount and type of fat and degree of fat oxidation in the diet, the presence of antioxidants, dietary selenium and physiological status of the animal. Other factors to be considered in assessing vitamin E needs of cows under commercial production conditions include: variability of vitamin E content in feedstuffs, poor stability of vitamin E during processing and storage of feeds and management practices resulting in over stressed animals. Selenium inadequacy is geographically widespread and can frequently be year-round problem. Dietary supplementation of vitamin E and/or selenium was found to decrease the incidence of mastitis and retained fetal membranes due to improved immune functions of the body. A known physiological consequence of vitamin E and selenium deficiency is reduced neutrophils activity. Supplementation of high levels of vitamin E (at least 1000 IU/h/d) during the dry period and early lactation can reduce the incidence of mastitis and reduced the prevalence of retained fetal membranes. Other study found that feeding 4000 IU of vitamin E/h/d during the last 2 weeks of the dry period resulted in an 80% reduction in clinical mastitis at calving and a 60% reduction in intramammary gland infections. Dietary supplementation of cattle with selenium results in a more rapid neutrophil influx into milk following intramammary challenge and increased intracellular kill of ingested bacteria by neutrophils. The interface between nutritional science and reproductive physiology provides considerable potential for optimizing reproductive efficiency in dairy cattle.