"...Copper deficiency usually arises due to a lack of copper in the animal's diet, particularly the dry matter component eg. plants...." More
"...once the sponge was removed impregnated ewes showed visible oestrus, and if inseminated 2 to 4 days after sponge removal showed high conception rates..." More
"Selenium is an essential trace mineral in sheep and cattle (Barragry 1994)..." More