Copper Deficiency and Toxicity in Goats

Episode 41
For the Love of Goats

If you’re confused by everything you’ve heard about copper needs in goats, then hopefully this episode will clear things up.

We are joined again by Dr. Robert VanSaun who teaches veterinary science at Pennsylvania State University and specializes in ruminant nutrition, and he debunks common myths while explaining symptoms of deficiency and toxicity, and how they are different, as well as where to start in your copper supplementation program. He also drives home the idea that all nutrition is local, and you can’t simply copy what someone is doing on another farm. 

Other episodes with Dr. Robert VanSaun

• #126 Brewers Grain for Goats
• #86 Urinary Calculi in Goats
• #37 Selenium Deficiency and Toxicity in Goats
• #39 Colostrum for Baby Goats
• #51 Zinc for Goats
• #57 Iodine Deficiency in Goats
• #65 Pregnancy Toxemia in Goats
• #66 Hypocalcemia in Goats

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TRANSCRIPT

Deborah Niemann 0:18
Hello everyone, and welcome to another episode. Today I am really excited to be joined once again by Dr. Robert Van Saun from Pennsylvania State University, where he teaches veterinary science. Today we are going to talk about a topic that is near and dear to my heart, which is copper deficiency. I think if my goats had not had a problem with copper deficiency many years ago when we got started, I never would have learned nearly as much as I learned about goats, because I had goats dying, goats not getting pregnant, goats not staying pregnant, goats with severe parasite problems even though they really shouldn’t have been having those kind of parasite problems… So we are going to talk about this today. Welcome to the show, Dr. Van Saun.

Robert Van Saun 1:03
Thank you, and glad to be back again.

Deborah Niemann 1:05
Yes. So first of all, can you just talk a little bit about why copper is important to goats?

Robert Van Saun 1:11
Sure. Copper is important to everybody. It was an element that originally, in the 1800s, was identified in plant tissue, and they thought it was just soil contamination. And they found it in animal tissue, and, again, thought it was just environmental contamination. And it wasn’t until the early 1900s that we actually determined that copper is what we call an “essential trace element.” So, like a previous discussion you and I had with selenium, copper is in that same relative range of a trace element. It plays many important roles. There’s many specific enzymes—many more than what we described for selenium—that are dependent upon copper. Probably the most famous, or the one that everybody knows the most, is an enzyme that’s responsible for making the melanin pigment. So that’s why, when an animal is copper deficient, they lose coloration. So a dark animal become sort of grayish-reddish hue to it. And that’s because they can no longer produce the melanin pigment. And then, copper is involved in heart function. Copper is involved in antioxidant status, and making red blood cells, and putting iron into hemoglobin, and nerve cell function, and normal development of the nerve cells themselves. So, copper is required by everybody. But copper is one of these trace elements that I call a double-edged sword. We can have copper deficiency, and also copper toxicity, very readily. So again, very similar to what we talked about previously, when we were discussing selenium. We need enough, but not too much. So the Goldilocks principle is always in place.

Deborah Niemann 3:21
Yes. And one thing I just thought about while you were talking, when you’re talking about how they can have problems with the color of their hair, one of the big myths that’s out there that I would love to dispel once and for all is that black goats are more likely to be copper deficient, or black goats need more copper. And my idea on this is that when a black goat is copper deficient, it turns this really icky rusty-red color. Whereas if a cream goat or a roan-red goat becomes copper deficient, it just turns white. So it still looks normal. So, can you just comment on that briefly?

Robert Van Saun 3:59
Yeah, that’s a really good point, Deborah. If an animal’s coloration is such that it requires more melanin pigment, then when the animal is unable to make the melanin pigment because of copper deficiency, they’re going to lose that coloration. It’s going to be much more obvious. So, you know, that’s why in the beef cattle industry, Angus cattle—black cattle—are much more recognized for copper deficiency than Herefords that have white faces or roan colors. We can certainly see the loss of color, but it’s just so much more obvious in a black-coated or black-colored animal just because of the massive amount of melanin pigment that’s necessary to maintain their natural color.

Deborah Niemann 4:48
Okay. And so when a goat becomes copper deficient, other than seeing the loss of color in their coat, what are some of the other symptoms that people would see?

Robert Van Saun 5:01
What I’ve seen in the work that I’ve been doing recently with sheep and goats becoming copper deficient here in Pennsylvania, because of some interfering substances that I’m sure we’ll talk about… The first thing I see is the herd starts to complain about either reproductive problems—that newborn animals, either some stillborns, greater stillborns than they expect, or a higher death rate of their young animals—their females not getting bred back in a very efficient way. And then finally, increased disease. And of course, with sheep and goats, the main thing we see is a much greater susceptibility to parasites. So in the younger animals, I see repeating issues of coccidia problems, or just increased fecal egg counts and more parasite problems with our adult animals.

Deborah Niemann 6:01
Okay, and then I know it’s a little tricky actually getting verification, because copper in the blood and copper in the liver don’t match up all the time.

Robert Van Saun 6:14
Yeah, that’s one of the challenges. Unlike what we discussed with selenium, where blood selenium was a good measure whether we did serum or whole blood, copper—we can measure it in the blood. And if it’s very high, or very low, we have a diagnosis. But if it’s within a range, which includes normality, or what the reference range would be, we really can’t interpret those blood values very well. And so it’s liver copper that is our best measure of nutritional status. Now, if we wanted to measure copper status in the presence of a disease process, then we could measure maybe ceruloplasmin, or some other copper-dependent enzyme, like superoxide dismutase—this is an antioxidant in our blood—those will go down. But that’s only when copper is extremely deficient in the animal showing clinical signs of disease.

Deborah Niemann 7:23
So the blood test can confirm but cannot rule out a problem with copper deficiency or toxicity.

Robert Van Saun 7:30
Yeah. So the best way to describe this is: We know that the relationship between liver and serum, or plasma copper, is challenging, because once you get above a certain value in the liver concentration, the serum copper… Basically it goes straight up and then levels off. So it’s not very discriminatory relative to changes in liver concentration. You know, it increases to a certain level above a very critically low value in the liver, and then beyond that, it’s not very dynamic in terms of reflecting differences. So typically, what I’ve done… Most of the work would suggest a level below 0.3 micrograms per mL. And the normal range in copper in the blood is somewhere between 0.6 and approximately 1 to 1.2 micrograms per mL. Now, we could still have a normal value in blood, but have a deficient liver value. But, should we find a value below 0.3, or better, many animals within a group below 0.3—so we’ve done some work. One of my mentors did some work where they bled a number of animals on farms and looked at the analysis. And statistically, they determined if we do about 10 to 12 samples, we can actually use blood as a diagnostic tool for copper. Now, that’s easy for me as a researcher to say, because, you know, my grant money pays for this. If I was an owner, and I needed to do 10 blood samples at, you know, $30 or $40 a sample, that’s a huge investment. That becomes problematic, you know. So the thing is, yes, I can use blood to some extent in evaluating copper status, both from a deficiency standpoint and a toxicity standpoint, but not very practical because of the economic impact.

Deborah Niemann 9:47
Okay. And in the selenium session, we talked about how you can send in a liver from any goat that dies, or a goat that you butcher, or a kid that’s a stillborn, or something like that. And you can do the same thing with copper, of course. But if somebody thinks they might have a problem, haven’t had a goat die, thank goodness, then how realistic is it to do a liver biopsy on a live goat?

Robert Van Saun 10:17
Well, it’s very realistic. I mean, a biopsy is always invasive. But in general we’ve performed, or veterinarians in general have performed, liver biopsies very routinely. And, you know, the problem is just sort of getting over that thinking that this is such a dangerous procedure. We can use ultrasound to guide the needle now to take the biopsy, and we only need a very, very small piece of tissue.

Deborah Niemann 10:49
Okay, that’s great to know! As someone who has had a needle biopsy, I’ll say it’s not that big of a deal. So it seems less intimidating.

Robert Van Saun 10:57
Well, that’s the factor—it is a big intimidating factor. And any invasive diagnostic tool like this, you know, always carries risks. But, you know, we’ve lowered those risks quite a bit. And again, we could certainly do less liver biopsies—just a select few to get our answer as opposed to taking 10 or 12 blood samples to get an answer.

Deborah Niemann 11:20
Right. So if you thought you had a problem, and you were going to do some liver biopsies, would you pick the goats that had the worst outward symptoms of deficiency or use some other metric?

Robert Van Saun 11:33
Well, the first thing I would do, before I jumped to the liver biopsy, would be to look at the diet and try and get a better perspective on how much copper the animal is consuming. We could do some additional, less invasive things—looking at liver function, liver enzymes, things like that—because, you know, one of the first things we would see in a toxicity case would be an elevation of liver enzymes, followed by kidney problems. But in a deficiency situation, I think what you described in terms of the roughest-looking animals, the animals that maybe have higher parasite loads, the animals that are starting to show some coloration changes, those would be the one or two targeted animals that I would want to take a sample from.

Deborah Niemann 12:25
Okay. And then one of the things that confuses a lot of people is that there’s a common thing that is said online, and that is that the symptoms for deficiency and toxicity are exactly the same. So there’s no way to know, just based on outward symptoms. And, in looking in the ruminant nutrition book—the complete name escapes me—the only symptom in common that they mentioned is anemia. So are there other symptoms that are exactly the same?

Robert Van Saun 12:59
Not so much. As we discussed, in the deficiency state we’re going to start to see some hair coat coloration; we’re going to, you know, maybe pick up on the problems on the reproduction side, or greater disease susceptibility. Those would be really the big things. On the toxicity side, as we mentioned: liver dysfunction, going off, feed not doing well… I really don’t see the hair color, or, you know, even as much as the rough hair coat. It depends on how much of the liver is damaged. In terms of anemia: Anemia is a consequence of copper deficiency. And the only time anemia would be an issue with copper toxicity is if the goat went into a situation of what we call “hemolysis,” where the copper ions get released into the blood and they start lysing, or breaking apart, all of the red blood cells. And so there you would see red-colored urine in the goats. That’s called hemoglobinuria, where the hemoglobin released from the broken-up red blood cells gets passed through the kidneys, and it causes kidney damage, and that would not be seen in a deficient state.

Deborah Niemann 14:24
This is really great information. So let’s talk about mixed minerals, because usually when somebody thinks they may have a problem with copper deficiency, first thing I ask them is, “What mineral are you using?” And it may be a “sheep and goat” mineral which has no copper in it whatsoever. Or, it may be some really cheap mineral that is mostly salt and it’s only got a teeny bit of copper in it, you know? So ever since we fixed our copper deficiency problem we’ve been using Sweetlix Meat Maker, which has around 1,700-1,800 ppm copper, and I really like that. And I do still give some copper oxide wire particles. And I’m fine with that to keep things balanced, because they also help with parasites. So that’s why I haven’t gone looking for something higher. But there are now some minerals on the market that have insanely high levels of copper that just scare the bejesus out of me. People send me these emails and say, “Should I give this to my goat?” And it’s got 5,000 ppm copper—or I even saw one one time that had 7,000 ppm copper. And that just blew me away. I mean, there’s no way I would put that out for my goat. So, what do you advise people in terms of, like, choosing a mixed mineral?

Robert Van Saun 15:43
That’s a good point. And that gets us into some of the real challenges in dealing with copper. First of all, if we just take one step back and think about what we discussed when we talked about selenium, we know that there’s a requirement. All right? So we have a requirement for copper. And if I look at the NRC, which is the National Research Council publication on sheep and goat nutrition, and look at what their perceived requirements are… So first of all, they suggest that the concentration—and again, we need to remember that concentrations aren’t eaten by goats, but that’s how we communicate. So, as you just said, Deborah, you know, “5,000 parts per million,” well that’s a concentration. And so it’s a matter of how many milligrams of copper is the goat consuming. All right? So that’s the first step. So, if I look at data for maybe about a 40 pound goat—so a younger goat—we’re looking at about 10 milligrams of copper a day. And then, as we move up, the highest requirement for copper is a goat that is pregnant with twins, and that runs about 50 milligrams a day. So that’s quite a range. Now, let’s put this in perspective. The maximum copper that the NRC would suggest for sheep is 18 to 20 milligrams. So for goats, we’re nearly twice that. So this is one of my pet peeves of the feed industry, in generating products that say “for sheep and goats.” If they contain mineral, somebody is either getting overfed or somebody is getting underfed.

Robert Van Saun 17:37
Now, when we think about requirements, as I said, we look at about 15 milligrams per kilogram of diet, or 15 parts per million, for lactating does. And then 20 milligrams per kilogram, or 20 parts per million, in the total diet for our maintenance and our pregnant and our growing animals. So, if we just take your example: So we have a product that has 5,000 parts per million of copper, and I’m going to convert that into milligrams per pound. So that’s 2,272 milligrams per pound. And then we can divide that by 16. So that’s 142 milligrams per ounce. And, if this is a salt-based mineral product for free choice, goats generally will consume about 1/4 to 1/3 of an ounce. So, if we just use 1/4, that’s 35 milligrams of copper coming from that product itself. So even though the number’s really big, it’s not potentially toxic unless the animal actually consumed way more of it than it should. And so, why we would use a product that’s that high is if we have a diet that’s very low in copper, our forages are very low in copper, or we have a lot of inhibitors of copper in the diet.

Deborah Niemann 19:23
Let’s talk about that. Because that’s our problem here. We now have a $2,000 water treatment system to help with this situation, but we had so much sulfur in our water before that, like, somebody would just walk in the front door of our house and they could smell it. Like, it was unbelievably stinky. So when people are like, “Well, I don’t know, I haven’t had my water tested,” I’m like, “You don’t need to have your water tested for sulfur.” If you got it, you know it, like, unless you don’t have a sense of smell.

Robert Van Saun 19:51
Right, right. Yeah, your typical sulfur, your soluble sulfates, and so on, if they’re high enough you’re going to get that what we call “rotten-egg” smell. And that’s going to be unpalatable for many parts, but it also will increase the sulfur intake in the animal. And sulfur by itself can interfere with copper availability; high iron in the water can interfere with copper availability; and the big one is molybdenum. This is a compound we usually don’t think about, and we traditionally don’t measure in our forages. But it is available; it’s just an extra cost. And so most of the research that was accomplished in the early 1930s through the 1940s, where they discovered this unique interaction between molybdenum, copper and sulfur. What happens is, in the rumen environment, facilitated by the bacteria, molybdenum and sulfur combine to make a compound called “thiomolybdate.” And in the rumen, depending upon the concentration of sulfur in the diet, the molybdenum in the diet, the acidity or alkalinity of the rumen, we can make various structural sizes of thiomolybdate. Typically in the rumen, under the usual conditions, the larger molecular weight thiomolybdates are made. And those bind the copper and hold on tight, won’t let go. And so what happens is that copper that was in the diet passes on through and out in the feces. And so essentially, even though you may have the normal milligrams of copper in the diet, because of the lower availability, those animals would become copper deficient. The lighter weight thiomolybdates can actually be absorbed. And it’s believed that they can bind to copper proteins in the blood and make those proteins dysfunctional. And so we can see various manifestations or clinical signs of copper deficiency in that state, even though your blood concentrations would be fairly normal. It’s just that the copper is bound to can’t do its work.

Robert Van Saun 22:33
So the research has suggested that a normal level of copper relative to molybdenum, or what we call the copper-molybdenum ratio, in the diet should be 6 parts copper to every 1 part molybdenum, up to about 10 parts copper to 1 part molybdenum. And if you drop below 4 to 1, that is leading you down the deficiency route. And if you’re above about 16 to 1, you’re at higher risk for toxicity. Now, one last thing I just want to say, because I know there’s so much interest in the copper oxide wire particle boluses. When you give those boluses, the copper is released in the abomasum, or the stomach. So it never sees the rumen. So that means that copper is not—even if you’re on a high molybdenum diet—that copper is not acted upon by the molybdenum, and so that copper is much more available to the animal.

Deborah Niemann 23:45
Oh, that’s very interesting. And then with the sulfur and the iron, those come from the well water, which, we have the iron, too. And then, if somebody is going to have excess molybdenum in their goats’ diet, where is that going to come from?

Robert Van Saun 24:00
Generally, that’s going to come from the forage. But it also can come in the commercial products that you buy. A lot of companies, to minimize their liability for potential copper toxicosis in sheep, actually add sodium molybdate to their feedstuffs. So, if you read the ingredient list on your mineral products or on your grain products, if you see “sodium molybdate” there, they’re adding molybdenum to it to try and basically tie up more of the copper.

Deborah Niemann 24:37
Okay. I have not noticed that. I have noticed, like, some of those that have the crazy high levels of copper in them—like the 5,000-7,000—that they will often have sulfur in them, which… I see that, and I’m kind of like, “Okay, so the sulfur is gonna bind with some of that copper, so it’s not really going to be absorbed that well”—

Robert Van Saun 24:54
Right.

Deborah Niemann 24:55
—”so maybe this is okay, to have that much copper in there, because the sulfur is going to balance it out?”

Robert Van Saun 25:01
Well, they probably don’t have that much sulfur, but certainly in the rumen what can happen is the bacteria can generate the sulfide ion from sulfur—from sulfur dioxide or sulfur sulfate molecules—and it makes a compound called “copper sulfide.” And that’s totally indigestible. So when when we talked about, you know, should we do a liver biopsy? I said, “No, you know, let’s look at the diet first.” So what I do is I get a forage test run, and I include molybdenum on it. And so then, from that forage, I calculate the copper to molybdenum ratio. And as I said, if it’s 6 to 1, to 10 to 1, that’s great. Normal molybdenum should be less than 1 part per million of dry matter. But I’m seeing forages… Matter of fact, I had a forage this year here in Pennsylvania for beef herd that had a molybdenum of 26 parts per million. And so there was no way… You know, I mean, if you think about it, if I wanted a 6 to 1 ratio, you know, I would have to multiply 26 times 6. You know, over 136 parts per million copper. Normal copper in our forages is about 9 parts per million here on the East Coast. It’s about 4 or 5 parts per million in the West Coast. So there’s a big difference of copper in our forages. We also can get very high copper in our forages. I’m seeing more forages that have 12 ,14, 15 parts per million copper than the 9. And so that’s worrisome on the sheep side. But that’s actually good on the goat side.

Deborah Niemann 26:50
So, I’ve read that alfalfa can be high in molybdenum. So when they say that, does that just mean if your soil is high in molybdenum? Or does it mean that alfalfa is especially good at pulling molybdenum from the soil? Or, what does that mean?

Robert Van Saun 27:08
Well, yes. So, the basic answer there is: Legumes in general, because of the bacteria in their root nodules that trap nitrogen, that process requires a molybdenum-based enzyme. And so they have more molybdenum in their roots and potentially in their plant tissue than a typical grass. Now, with that being said, we’re in the two-year field study where we have fertilized orchard grass and alfalfa with a traditional lime fertilizer as well as a fertilizer that is spiked with molybdenum. And what we were able to show is we actually got higher molybdenum concentrations in orchard grass than we saw in alfalfa. So, across the board, the generalized information would suggest legumes typically are slightly higher, but when we talk higher, we’re only talking like 0.8 to 1.2, 1.5 parts per million molybdenum versus less than 0.5 to 0.8. But, in this situation, we were able to get molybdenum concentrations up to 8, 9, and 10 parts per million. So that’s really significant. And that’s going to have a huge impact on copper availability. Now, we also found that, when we add lime to our soils, molybdenum is different than all the other trace elements; it’s actually absorbed more efficiently by the plant in neutral pH soils than in acidic soils. Whereas all the other trace elements are absorbed more efficiently by the plant in acidic soils than a neutral pH.

Deborah Niemann 29:13
And so, kind of bottom line then: What is your recommendation for people in terms of making sure that they succeed with that Goldilocks principle of not having too little and not too much copper in their goats’ diet?

Robert Van Saun 29:31
All right. So again, it’s all going to start with looking at the feeds. I would want to test my forages, and copper is a regular nutrient that gets tested for within a regular forage test. The molybdenum does cost extra, but I think it’s $12. And that is certainly peace of mind. And so that’s where I start first. But then, as we’ve talked about, I do look at the grains, or the mineral mix, or both. And first, I look at the ingredient list to see if sodium molybdate is on it. And if not, you know, I still may have that tested for molybdenum. I do the same thing for the mineral.

Deborah Niemann 30:22
Oh, this reminds me: So one of those companies that has got the crazy new high level of copper, I actually sent them an email and said, “Do you have research that you can show me that shows that this level of copper is safe?” And they sent back a study that only lasted for three months. And, at the end of three months, they harvested all of the goats, because they were meat goats, and they had liver levels around 400, 500 ppm copper, which sounded really high to me. But they said that that was fine, because there were no lesions on the liver. And I’m thinking, “Well, give it a couple more months, and they might have had lesions on the liver!” Like, three months to me just didn’t sound very long.

Robert Van Saun 31:12
Yeah. No, they… Again, it depends on how they displayed that concentration. So 400 to 500 parts per million of copper in the liver, when it’s presented on what we call a “dry matter basis”—that’s a normal liver concentration for most species. If that was on a wet matter basis, a wet weight basis, then, to put that in perspective on a dry matter basis, liver dry matter is approximately 32%, 33%, so we’d multiply it by three. And then that would put it up around 400 times 3—that’s 1,200 parts per million. That’s the toxicity. So they could actually survive with that. But, if they had any kind of insult, or something that disturbed the liver function in some way, they’d start spilling that copper out, and that would cause necrosis of their liver, and they would just acutely die. So this is the problem, is copper has to be excreted by the body through the bile from the liver. And copper will accumulate in the liver for months and months and months. But then it takes some insult, maybe transportation, maybe pregnancy with parturition, maybe bringing in a new animal and having the social hierarchy reestablished—that could be a stressor enough that’ll cause spilling of those copper ions. You know, they’re trapped by proteins within the cells. But stressors can release that, because the stress hormones stimulate the liver to form acute-phase proteins that help fight off infection and so on. And copper is one of the compounds that’s excreted from the liver in an acute-phase protein called “ceruloplasmin.” And so that can spill out. And copper ions—free ions—in the blood will cause all kinds of oxidative damage to the red blood cells and other things. So, you could have a perfectly looking normal animal, and then it hits that insult, and then they’ll be dead within 48 to 72 hours.

Deborah Niemann 33:34
That is such good information. And all of this has been such good information. And I know there’s a ton of misinformation out there about this. And so many times, you know, people contact me and say, “What should I do?” And it’s like, “Well, start with a mineral that’s got around 1,700-1,800 ppm and see what happens.” That may be perfect for your goats. That’s a well-established level to start with. Because your goats may be fine with that, you know, if you don’t have any antagonists in your environment and stuff. And then, if you do have problems, then you start working from there.

Robert Van Saun 34:07
Right, right.

Deborah Niemann 34:09
Well, this has been terrific! I learned a lot, as always, and I will be listening to this again and again—even though I took notes, I’m gonna listen to it again and take more notes, because this is just great information. So many little nuggets here that, you know, one little nugget may be helpful to one person, and another little nugget may be helpful to somebody else, because everybody’s situation is different. And when people tell me that, “Well, it shouldn’t be this hard,” I always remind them that goats are not natives of North America. And so, in many places—if you really want to have just a totally natural environment—in many places, that means goats would become extinct, because the land just doesn’t have what they need. So, since we brought them over here, it’s our responsibility to take care of them and make sure that they get what they need to thrive.

Robert Van Saun 34:55
And again, as the saying goes, you know, “All nutrition is local.” It all depends on your local environment. And so we can’t just adopt a nutrition program that somebody is doing in the state of Oregon, or Colorado, or whatever, no matter how good they’re doing, just because it’s not the same.

Deborah Niemann 35:18
Yeah. Well, thank you so much. This has been terrific. It has been such a pleasure to have you back again.

Robert Van Saun 35:23
All right, thanks.