by Ulf Kintzel
Articles warning of copper poisoning in sheep appear frequently in various publications. This leads people often to believe that sheep should have no copper in their diet. However, copper is essential for a sheep to even exist. So how likely is copper poisoning?
Let’s examine why sheep are more likely to get copper poisoning than other species that are more tolerant of this element such as goats. Simply stated, sheep have a greater difficulty disposing of excess copper than other species of animals. If there is an excess of copper in a sheep’s diet, it is stored in the liver. It is then only slowly disposed by the sheep’s liver. Over time excess copper will accumulate. When the animal is stressed, the copper is released all at ones into the blood stream. This is called chronic copper poisoning and is more common than acute copper poisoning. Death is certain when a sheep shows symptoms. Treatment options exist theoretically speaking but are not practical or feasible in real life. However, chronic copper poisoning does not occur as a widespread outbreak. Only one or at the most a few individual animals will die at any one time.
Because of the sensitivity to copper, feed stuff and minerals for sheep have no copper added, which is often confused with not containing any copper. Most feed stuff, be it forage or be it grains, does contain copper. In fact, sheep need copper for very important biological functions. For instance, the development of the central nervous system requires copper. That means there is also the real possibility of copper deficiency. This article makes the attempt of putting both copper poisoning and copper deficiency in perspective.
About twenty years ago, I used to feed minerals designed for cattle that had copper added. I did so because minerals designed for sheep were unavailable to me at that time or at least not obtainable at a reasonable price. I did that for a few years without any negative impact to my flock of Texel sheep, which I ran at that time. Finally, I got a hold of a representative of a feed supply company and was now able to receive minerals for sheep. The same year, I pastured my sheep most of the winter on residue on heavily limed hayfields. Lambing came around in late winter and I had an unusual number of still born lambs. Many of the lambs that were born alive had a retarded suckling reflex and died despite of all the help shortly after birth. I had epidemic-like losses. The diagnosis was copper deficiency. The limed fields had aided the problem since lime reduces the amount of available copper in plants.
I read up on the subject of copper deficiency and ever since then I feed free-choice minerals with added copper right around the time when my ewes are 100 days into gestation. That is when the central nervous system of the un-born lambs develop and copper is essential for it.
Let’s also remember that copper sulfate used to be used as a dewormer for sheep and indeed I use it from time to time as a dewormer still by throwing once in a while a small handful into the water trough.
Over the years following the incident of copper deficiency, I had gotten lax about added copper in minerals or salt with added trace minerals (which includes copper) and used it indiscriminately. It caught up with me. One year I lost one sheep in the fall and the following winter another due to chronic copper poisoning. Since I didn’t want to risk the health of my expensive new rams I discontinued the liberal use of minerals with added copper for a while. Instead, I deliberately use minerals or salt with added copper at certain time intervals, especially at the time when my ewes are right around the 100 day mark during pregnancy.
A word of caution: my experience is limited to minerals and salt with added copper. I don’t know what the effect would be if one were to feed a grain mixture with added copper. I don’t feed any grain since I have been grass-fed for many years. I would suspect that the effect would be much more pronounced simply because of the greater amount of grain consumed compared to minerals and therefore also a far greater amount of consumed copper. Any grains that are being fed already contain copper, which makes in my view copper deficiency in grain-fed sheep highly unlikely.
Over the years, I came to this conclusion: Many articles have been written about copper poisoning in sheep that warn time and time again against feeding feed and minerals with added copper. They are warranted given a sheep’s higher sensitivity to copper when compared to other animals like goats or cattle. Very little is being said about copper deficiency. Copper deficiency is a real possibility in grass-fed sheep, especially when limed fields or moorland pastures are grazed, which are often low in available copper. While copper poisoning often only claimed a sheep or two when it occurred at my farm, copper deficiency was devastating when it happened. I have adjusted my schedule of feeding minerals with added copper to avoid such devastating loss due to copper deficiency.
Ulf owns and operates White Clover Sheep Farm and breeds and raises grass-fed White Dorper Sheep without any grain feeding and offers breeding stock suitable for grazing. He is a native of Germany and lives in the US since 1995. He farms in the Finger Lakes area in upstate New York. His website address is www.whitecloversheepfarm.com. He can be reached by e-mail at firstname.lastname@example.org or by phone at 585-554-3313.