Relationship between selenium content of forage, blood and organs of sheep, and lamb mortality rate.

The investigation comprised 12 herds, totalling 660 sheep, in the counties of Stockholm and Uppsala. The selenium content of specimens of forage, whole blood, muscle, liver, and kidney was determined by a fluorimetric method. Data on the number of born and dead lambs were collected 4—5 months after lambing. Dead and sick lambs were subjected to necropsy and to clinico-chemical analyses, respectively. The selenium content of hay and corn was lower than 60 ng per g, which some authors regard as the minimum level of Se requirement for protection against white muscle disease in sheep. The analyses of forage mixtures containing oil concentrates and beet pulp showed selenium levels that were about 2—5 times as high as this minimum level. In herds in which the animals had not been treated with selenium preparations prior to sampling, there was a significant positive correlation between the selenium content of the forage and that of whole blood. A relationship was also noted between the selenium content of forage and of organs. In 9 out of the 12 herds the selenium concentrations in whole blood were on the level that is considered to be representative of white muscle disease. A high mortality rate was recorded for lambs whose mothers had low selenium levels in their blood. Prophylactic and curative treatment with selenium plus vitamin E orally and/or parenterally probably reduced lamb mortality rate in the herds fed a low-selenium diet.