Wichtel J J
Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada C1A 4P4.
N Z Vet J. 1998 Apr;46(2):47-52. doi: 10.1080/00480169.1998.36055.
SELENIUM AVAILABILITY: Selenium deficiency has been an important source of loss to the pastoral industries of New Zealand. About 30% of farmed land in New Zealand is considered to be selenium-deficient and continued development of soils and pasture will tend to further decrease the concentration of selenium in pasture.
Formerly it was believed that all biological functions of selenium in animals could be attributed to the antioxidant activity of the enzyme glutathione peroxidase. More recently, it has been shown that selenoproteins have roles in immune function and thyroid hormone metabolism.
Following supplementation of ruminants grazing pastures deficient in selenium, milk production and growth responses are likely to occur in cattle, while in sheep improvements in growth and fertility are most likely. Reproductive dysfunction may not be as important as previously thought in cattle grazing pasture moderately deficient in selenium. The relationship between selenium intake and disease resistance deserves further study.
Management of selenium deficiency will continue to be important in grazing ruminants. Veterinarians should be aware that many selenoenzymes exist, some with functions quite distinct from the antioxidant role of glutathione peroxidase.
硒的可利用性：硒缺乏一直是新西兰畜牧业损失的一个重要来源。新西兰约30%的耕地被认为缺硒，土壤和牧场的持续开发往往会进一步降低牧草中的硒浓度。
以前人们认为硒在动物体内的所有生物学功能都可归因于谷胱甘肽过氧化物酶的抗氧化活性。最近有研究表明，硒蛋白在免疫功能和甲状腺激素代谢中发挥作用。
在给放牧于缺硒牧场的反刍动物补硒后，牛可能会出现产奶量增加和生长反应，而绵羊最可能出现生长和繁殖力提高的情况。对于放牧于硒含量中度缺乏牧场的牛来说，生殖功能障碍可能不像以前认为的那么重要。硒摄入量与抗病能力之间的关系值得进一步研究。
对放牧反刍动物而言，管理硒缺乏问题仍将很重要。兽医应意识到存在许多含硒酶，其中一些酶的功能与谷胱甘肽过氧化物酶的抗氧化作用截然不同。
