There is a lot of confusion regarding copper and sheep. Many have been told for years to steer clear of copper in sheep feeds and rations no matter what. However, the truth is a little less black and white than that.
Sheep actually have a daily copper requirement. Copper is essential for a variety of key systems in the body and is needed for immunity, reproduction and growth. Copper plays a vital role in wool production, stress resistance and hoof integrity. Copper deficient sheep have steely wool that is lacking in crimp and tensile strength. Lambs born to copper deficient ewes may experience congenital nervous disease. These sway back lambs may have difficulty standing or walking and may die due to inability to nurse.
So if sheep actually NEED copper, why have producers been told to avoid it all of these years? The answer is that sheep, particularly wool breeds, have difficulty excreting excess copper. As such, they are very susceptible to copper toxicity if excess copper is ingested.
Occasionally, sheep supplements or feeds may have copper listed on the guaranteed analysis due to regulatory requirements. Because copper is a naturally occurring element in soils, common feedstuffs contain a low level of copper—what we call “background” levels. Current rules outlined by the Association of American Feed Control Officials (AAFCO) state that copper minimum and maximum levels are required on labels for sheep or goat products where the amount of copper in the formula is at, or exceeds, 20 ppm.
In simplistic terms this means that the background levels of copper are at 20 mg per 2.2 lb of product (9 mg copper per pound) or greater. When a formula contains less than 20 ppm copper, no copper guarantee is required and thus those labels will look different than those of formulas containing 20 ppm copper or greater. To give you a point of reference, the copper concentration would need to be at 700 ppm for a 1 oz intake or at 175 ppm for a 4 oz intake to approach what is commonly accepted as toxic levels for sheep.
The take-home message from all of this is that if a commercial product is legally labeled for use in sheep, it is safe for use in sheep-- whether or not copper is listed on the label. If you have questions, as always, call the manufacturer for clarification.