Copper and sheep. Is copper going to kill my sheep? The title says it all. There isn’t a more misunderstood, maligned nutrient in sheep. You’ve probably heard that copper is evil. Sheep can’t have any copper. If sheep have copper in their diet they will die. Unfortunately, while sheep can and do die of copper poisoning, these are all inaccurate statements.
Sheep DO have a copper requirement. They can become copper deficient. Sheep can die from a copper deficiency, and it can be devastating to your lamb crop. So instead of villainizing an essential nutrient, let’s take a few minutes to take a quick look at the complicated nuances of copper and sheep. If we take the time to understand the relationship sheep have with copper we can manage nutrition properly rather than with irrational fear.
So, what is the deal with copper and sheep?
Copper is an important nutrient for animals, including sheep. It is required for making red blood cells, and supports wool or hair growth and pigmentation. Copper is also essential for nerve function, bone formation and white blood cells. So clearly some pretty important stuff. As you can probably tell from this list, a diet completely devoid of copper would be a very, very bad thing for your sheep.
And indeed it is. Sheep who are deficient in copper will have poor quality wool. The animals will likely be poorly conditioned and not thrifty. They will also likely be anemic and have poor fertility and conception rates. Lambs will have weak bones and be prone to fractures. Lastly, one of the most severe symptoms is neurological—swayback/enzootic ataxia—weakness, lack of coordination, tremors, and or paralysis. Swayback can be seen in newborn lambs if ewes are deficient during gestation. Sometimes it doesn’t appear until the lambs are older. Either way it is incurable as it results from impaired nervous system development as a fetus. Clearly sufficient copper levels are extremely important for the survivability and profitability of your sheep.
So why then is copper frequently stated as such a bad thing for sheep?
The why is simple. As compared to cows, goats, or horses, sheep have a very low copper requirement, and a very narrow safe range between deficient and toxic. For example, sheep need 4-11ppm copper (dry matter diet), but reach toxic levels between 15-25ppm. Goats on the other hand need 15-25ppm, but don’t reach toxicity levels until 70ppm. As you can see it is much easier to safely dose goats with copper because your safe range is much wider. It is very easy to poison a sheep with copper. This is what makes copper such a complicated topic with sheep.
In most forages in most places in this country the levels of copper are sufficient to meet the dietary needs of sheep without supplementation. This is why it is typically not recommended to feed sheep copper. It is not that your sheep aren’t eating copper, and that any copper at all in their diet is automatically going to kill them. It is simply that they typically don’t need extra added copper like other species do.
The levels of copper put in feeds for horses, goats, cows, pigs and poultry are too high for sheep to tolerate. The 15-25ppm goats need to not be deficient is a toxic level of copper for sheep. Thus, it is not recommended to feed your sheep EXTRA copper unless there is a documented deficiency. And this is what often gets mis-understood or misconstrued as sheep can’t have any copper, ever, period.
However, if your sheep are proven to be deficient you can carefully feed them copper supplements.
There are reasons that sheep can be copper deficient. Two of the most common reasons are grazing pastures very low in copper, or feeding forages with high molybdenum and sulfur levels. Nutrition is complex and nutrients do not exist in a void. They interact with each other in the soil, plants and animal’s bodies. High levels of sulfur and molybdenum bind up copper in the rumen making it unavailable. So in some cases even though it looks like their diet should be sufficient in copper on paper, deficiencies can still occur. Thus, it is important to holistically look at the picture when dealing with copper.
If you are going to feed copper to your sheep, it should be done very carefully and under veterinary supervision.
You should have symptoms eg. swayback in lambs and/or do testing to determine copper levels. Liver testing is the most accurate. Blood testing is not at all accurate. Pasture tests can also be very helpful to gaining insight into what your animals are consuming. They provide a rough estimate of what is available, and any potential nutrient interactions that might be occurring. They will also tell you if the copper levels present in your forages are a red flag for poisoning. However, they do not definitively tell you whether your sheep need supplemental copper or not.
If you are fairly confident that copper deficiency is causing the symptoms your sheep are showing, the definitive way to know for sure is to do a response trial where you supplement part of your flock with copper and not the other part keeping all other variables the same. You should supplement the minimum amount of copper required to resolve symptoms. For example, some flocks with documented copper deficiency problems only provide additional copper to pregnant ewes during gestation which allows their bodies to use up excess copper throughout the rest of the year to prevent accidental copper poisoning.
There are two ways sheep can get copper poisoning.
Copper poisoning can be acute or chronic. Acute poisoning is due to them gobbling a huge amount of copper accidentally. This has been known to occur from things like feed mills mixing feed incorrectly or sheep breaking into the chicken feed. Chronic poisoning is trickier. It is the result of feeding a little bit to much over a long period of time.
Sheep are extremely good at storing copper in their liver, and if their liver gets overwhelmed (often by a stressful event) they can release all the accumulated copper causing acute toxicity and death. Thus, it is important to make sure you are supplementing enough, but not too much copper to your sheep. If you are supplementing copper to eliminate deficiency symptoms, the best way to monitor the copper status of your flock over time is to take postmortem liver samples of culled animals.
It is also worth noting that different breeds of sheep have different copper tolerance levels.
Some breeds like Katahdins or Merino are more tolerant of higher copper levels. Some like Texel and Suffolk are very susceptible. So it is a good idea to research the susceptibility of the sheep you are keeping. Be even more careful about copper consumption in highly susceptible breeds.
It is also important to note that sheep can consume toxic levels of copper from forages alone. Though many copper poisoning incidents are a result of things like incorrect feed mixes, not all are. For example, it is not a good idea to graze sheep on land that has been fertilized with swine or poultry manure or on orchards sprayed with copper fungicides as they can cause toxicity. Thus, it is always a good idea to test forages and feed ingredients if there is any question about whether it is safe to feed.
As a sheep producer, you don’t have to irrationally fear copper. Treat it with respect. It’s dangerous, but also essential. Education about your animals’ needs and the copper levels of the available feed is your best defense against doing it wrong.
If you don’t have deficiency symptoms, avoid feeding your sheep extra copper. If you do have symptoms, don’t fear feeding copper to the point that your animals suffer. Work carefully and closely with a vet or nutritionist to determine the level of copper supplementation required to cure the deficiency without creating toxicity problems. Hopefully this has shed some light on the confusing, feared topic of copper and sheep so that you can more effectively make decisions for your flock.
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