The importance of selenium and the effects of its deficiency in animal health

Selenium (Se) is an essential trace element in animal nutrition, and exerts multiple actions related to animal production, fertility and disease prevention. Glutathione peroxidase (GSH-PX) enzyme was the first proven selenoenzyme that can prevent oxidative damage of the cellular membrane. Actually more than 30 selenoenzymes have been described and a hierarchy process for expression in the animal has been established. White muscle disease (WMD) was the first recognized condition associated with Se deficiency. WMD causes new born mortality, especially in ruminants, and impaired production condition in growing and adult animals. Selenium is critical to thyroid hormone synthesis and it is also very important for converting T4 (thyroxin inactive form) to T3 (active form). A good immune response requires Se too. Selenium status in soil, plants and animal blood and tissue can be used in the diagnosis of Se deficiency. Diverse forms of Se supplements are available, but many factors affect their activity and efficacy, such as its chemical form and animal's health and production condition. The relationships between foetus Se metabolism and pregnant dam Se status are critical for productivity and need further research. (C) 2010 Elsevier B.V. All rights reserved.