|Blood Se (nmol/L)|
|Serum Se (nmol/L)|
|Blood glutathione peroxidise (GSH-Px) (kU/L 25°C)|
|Liver Se (nmol/kg fresh tissue)|
|Pasture Se (mg/kg DM)|
1. The data have been obtained from Se supplementation / animal response studies using blood Se as the index of Se status.
2. The data sets are reasonably robust for sheep and cattle. The deer data are based on several studies.
3. The criteria for serum, GSH-Px and liver have been determined from the relationships between blood Se and the above parameters.
4. Blood Se concentration is the best criteria to use to assess Se status of livestock.
5. There have been a number of studies, particularly from the USA with dairy cattle, that have developed criteria different to those established in New Zealand. The reference ranges for blood Se concentrations (nmol/L) for dairy cattle in the USA are: <750 is deficient and >1500 is adequate, while dietary Se requirement is 0.3 mg /kg DM. The USA do not appear to have the Se supplementation / cattle response data similar to that which is available for New Zealand livestock. They have some studies that show a decrease in the incidence of mastitis and retained placenta in dairy cows when they supplemented with Se or Se and vitamin E. Further, indoor feeding and management of dairy cows in the USA means that the intakes of vitamin E in these cows are lower because of the deterioration of vitamin E in stored forages when compared with pasture fed cattle and the challenges to diseases would be greater.