The Biological Basis for Selenium Requirements of Animals

Most of the available data on Se metabolism and estimated dietary needs are based upon maintenance of Se levels and(or) GSH-Px activities in blood. These measures are not specific enough to animal health and performance to be used for sole justification for Se supplementation. The associations shown thus far between Se intake and health issues such as mastitis, impaired reproduction, heart disease, and cancer are correlations and few clear cause-and-effect relationships have been established. Although .3ppm dietary Se appears to more fully satisfy the dietary need for Se in most animals than .1 ppm, more scientific data are needed to support the higher level. As more research is completed on the relationships between Se and immunity, reproduction, and certain health disorders, assessment and monitoring of appropriate levels for Se supplementation should be continued.