Part Two - Copper in Small Ruminant Nutrition
Kendra Rudd Shatswell Hefty Goat Holler Farm I am not a veterinarian. I am not a nutritionist nor a scientist nor a formal researcher. I am just a girl that loves goats. I want to take care of them to the best of my ability, and so I strive to LEARN. I like to share what I learn, but please do check out all the resources provided! Special thanks to Kathy Winters of Red Horse Valley LLC!
Copper is a vital trace mineral. The functions of copper and the dietary requirements are not entirely understood, but here’s what we have learned about copper in small ruminants thus far. Take these facts with a grain of salt, because some new research might surprise you. Functions of Copper If you have the time, read source 4 in its entirety – it is incredibly detailed and helpful. Copper is important for melanin production – which is responsible for coat color – and for keratin synthesis – which is needed for healthy hair, hooves, and horns. It is important for iron transport and metabolism and thus is essential for the formation of red blood cells. Furthermore, copper is an important factor in proper immune system function such as the formation of antioxidants, for nerve conduction and for strong, healthy connective tissues and bones (1, 4, 5). It often works with other minerals to create vital enzymes. Copper is important to fertility; specifically, it is thought to be an “enzyme component and catalyst involved in steroidogenesis and prostaglandin synthesis” (1).
Sources of Copper and Bioavailability Forage, hay, feed, mineral supplements, and medicines can all provide copper – even water delivered by copper plumbing can contribute to your goat’s daily intake of copper. Copper is more readily bioavailable in concentrates like grain than it is in fresh forages. Hay is typically a better source than grass. Legumes, especially subterranean clovers, promote copper storage in the liver (7). Alkaline soils can decrease the copper intake of plants – this often occurs when pastures are limed or fertilized (2). As I mentioned in Part One, adult ruminants do not excrete copper as well as non-ruminants. Furthermore, "Copper absorption in ruminants is low (<1.0–10.0%) relative to values reported in nonruminants. The low absorption of copper in ruminants is largely due to complex interactions that occur in the rumen environment” (6). Horse, pig, and chicken feeds might be especially high in copper, as can be dog and cat food, which should never be fed to ruminants like goats but might be palatable to goats nonetheless (5). I found it interesting that toxic plants like lupines and alkaloid-containing species can exacerbate copper absorption, resulting in toxicity (3). Copper is cumulative, so when excess is ingested from any and all of these sources, it is stored in the liver and can be stored for a very long time – some sources say more than a year without clinical signs (4). The liver might release massive amounts of stored copper due to stress such as castrating, being chased, or from liver damage, resulting in hemolytic crisis, where red blood cells are destroyed faster than they are made. Some forms of copper are more bioavailable than others (2,6). Chelated copper and copper sulfate (what will you will usually see on your mineral and feed tags) are the most available, while copper oxide in copper boluses is the least available – “only one-third digestable as copper sulfate” according to Smith and Sherman (2). Copper Toxicity Symptoms Copper toxicosis might occur from ingesting too much copper at once. Chronic copper toxicity usually occurs when there is a mineral imbalance, especially a lack of copper antagonists, in the diet for a long period of time. According to Merck Vet Manual, signs of toxicity include: “depression, lethargy, weakness, recumbency, rumen stasis, anorexia, thirst, dyspnea, pale mucous membranes, hemoglobinuria, and jaundice” (12). Other studies and cases have indicated teeth grinding, drooling, diarrhea, increased respiratory and heart rates, and dark-colored urine. Renal failure and liver necrosis are possible. In advanced stages, the animal might become recumbent and show “neurological abnormalities such as paddling and vocalization” (2). The animal might just be found dead.
Copper Deficiency Symptoms Signs of copper deficiency include infertility, especially delayed or depressed heats, abortions, and dead fetuses. Congenital ataxia, also known as “swayback,” is a copper deficiency induced neurological disease that occurs at birth – this is not to be confused with the “swayback” in horses – and is characterized by “depression, head shaking, trembling, and ataxia.” (10). A delayed onset (1 week to 6 months old) is called enzootic ataxia and usually begins with the hindlimbs – the kids become increasingly incoordinated until recumbent. Spontaneous bone fractures and stiff limbs can also occur in copper-deficient animals. Other clinical signs of deficiency include anemia, lightening of coat colors, diarrhea, general ill-thrift, and weight loss. Both copper toxicity and deficiency has been shown to impair immune system function in animals (4). As I’m sure you noticed many of these symptoms are frustratingly vague or could have many other causes such poor diet or parasitism or diseases like Johnes…goats just can’t be simple, can they? This is why tissue testing on deceased animals is so important! By testing the liver and kidneys, you can get a much better idea of the copper levels in your herd.
Daily Requirements and Mineral Relationships How much copper does a goat need? It depends. Animal factors like age, size, breed, and general health affect the requirement – need can vary from animal to animal within the same herd. There is evidence certain breeds like Boers and Angoras might be more susceptible to copper toxicity while it is hypothesized that “dwarf” breeds might require slightly more (3, 13). We know late gestation does require more copper than dry does. Non-ruminating kids absorb copper better than ruminating adults. The environment also matters – as mentioned earlier, stress is a key component in copper toxicosis. The presence or absence of copper antagonists is a major deciding factor in the daily intake requirements, so before we can slap a couple numbers up there, we need to learn about important mineral relationships. Arguably the most important relationship is that of copper, molybdendum, and sulfur. Sulfur and molybdendum are both copper antagonists. Together, they can form thiomolybdates in the rumen, which “form insoluble complexes with copper that do not release copper even under acidic conditions” (6). This not only makes copper less bioavailable to the goat, it increases copper excretion from the liver and through the urine (14). The copper x molybdenum x sulfur interaction is very complex. For more detail, I highly recommend reading source 14 by Suttle, “The Interactions Between Copper, Molybdenum, and Sulphur in Small Ruminant Nutrition” – at the time of this writing, the full PDF is available for download. Another excellent resource is at https://pubs.usgs.gov/sir/2017/5118/sir20175118_element.php?el=42 where you can find detailed maps of the soil concentrations of molybdenum and other elements. Generally speaking, it is recommended the copper to molybdenum ratio be greater than 5:1 but less than 10:1 on a dry matter intake basis (2). Molybdenum requirements are not well-defined but are thought to be between .1ppm and 3ppm, with toxicities common >3ppm (16).
Sulfur can also interact with copper independently of the copper x molybdenum x sulfur interaction. Excessive sulfur can hinder copper absorption in ruminants, but exactly how much is excessive depends on what source you read – an older source (17) indicates it takes 3500 to 5000ppm to interfere but a newer source claims (3) 2000ppm is sufficient to antagonize. Well water is a common source of sulfur, but without an analysis on the water, you probably cannot accurately guess the amount of sulfur. It is important to remember that lactating does, especially smaller does that are high producers, might drastically increase their water consumption. Zinc is also an important copper antagonist. For beef cattle, the zinc to copper ratio is recommended at 3:1 on a dry matter intake basis when on pasture and 4:1 DMI when the diet is primarily hay and concentrates (2, 3). Current zinc recommendations are a minimum daily intake of 10ppm, with 45-50ppm being the requirement of a standard diet and 75ppm in diets with serious antagonists. As mentioned in Part One, zinc cannot be stored so thus must be consumed daily and absorption is highly variable. Sulfur, calcium, and copper are important zinc antagonists (2, 3). In some literature, iron levels greater than 350 to 1000ppm has shown to be antagonistic to copper absorption, while some studies indicate the range might be closer to 250 to 1200ppm (6). Well water and legumes are common sources of excessive iron, but I also thought it was interesting that “recent research suggests that acid conditions occurring during the fermentation of silage and haylage greatly increases the bioavailability of iron from soil contamination” (6). Calcium, cadmium, lead, selenium, manganese, and Vitamin C are also documented copper antagonists, though of less importance. It was difficult to find detailed information on these. Excess calcium is considered anything over 1.5% of the dry matter diet, according to the Nutrient Requirements of Small Ruminants 2007. Cadmium blocks a protein necessary for copper absorption (18) and interferes when there is more than 3-7ppm in the diet (3). Manganese requirements also vary widely by author, but it is thought 40ppm is adequate and an excess of 500ppm antagonistic (2). Below is a mineral wheel for reference. I was unable to find the original source of this photo, so if anyone is aware of that, please let me know.
Common Recommendations With all of those eye-crossing relationships in mind, now we can suggest some numbers for copper requirements…maybe. Recommendations vary WIDELY. The National Research Council has not set a maximum but suggests “a cautious approach would be to use the cattle level of 40ppm dry matter in usual management” (NRC 2007). Smith and Sherman suggest a standard diet of 10ppm, a minimum of 7ppm, and 14ppm in the presence of interference from other minerals (2). Langston University recommends anywhere from 10ppm to 80ppm without any explanation as to the great variation though there is a note elsewhere on the site that “copper levels are of limited value in assessing adequacy unless forage concentrations of copper antagonists such as molybdenum, sulfur, and iron are also considered” (9). Pugh and Baird suggest 4-15ppm, with a note that “copper, molybdenum, sulfur, and iron concentrations of the diet should be determined” by body tissue concentrations if copper deficiency is suspected (3).
Remember that both the copper content of each potential source AND the intake need to be determined to get a good idea of the animal’s total daily intake of a mineral. For example: on my farm forage and hay constitute the majority of the goats’ diets. So, even though it may have lower copper ppm than the concentrate I feed, forage and hay would provide more copper because the goat is eating more of it than concentrate. Sorry, but figuring daily intakes will take some math. This is the “easiest” explanation I have found, to date. Don’t ask me if I can explain it, because I can’t – math makes my brain go belly up. https://extensionpublications.unl.edu/assets/pdf/ec288.pdf
I talked about Pat Coleby’s mineral mix in Part One, cautioning that her circumstances were unique in that she lived in an *incredibly* copper-deficient area of Australia. After doing some math (yuck) I estimated the total ppm of copper in 50lb of the Pat Coleby mix. 27,500ppm copper. No, that is not a typo. A similar explanation can be found here: https://colliefarm.wordpress.com/2009/12/26/if-pat-coleby-had-a-label/ In her book (there are many editions, so I am not sure which edition) she estimates that daily intake at about 5g or .18oz a day for a 150lb animal. 5g of 27,500 ppm = 0.005 kg x 27500 mg/kg = 137.5 mg of copper per estimated daily intake.
For comparison – a few popular goat minerals: Remember that .5oz is equal to a bit over 14 grams. Stockade Meat Maker and Sweetlix Meat Maker have a copper content of 1810ppm maximum in a 25lb bag and is to be fed at the rate of .3-.5ounces per day for a 150lb animal. 14 g of 1810 ppm = 0.014 kg x 1810 mg/kg = 25.34 mg Right Now® Onyx has a copper content of 2500ppm minimum in a 50lb bag. It is formulated for beef cattle and so has no daily intake estimate for goats.
Purina Goat Mineral now contains 2700ppm maximum copper in a 25lb bag and is to be fed at .25 to .3oz per head per day. 8.4 g; 0.0084 kg x 2700 mg/kg = 22.68 mg
Manna Pro Goat Mineral has 1350ppm of copper for an 8lb bag and is to be fed at the rate of .25-.5oz per goat per day. Manna Pro 0.5 oz = 14 g; 0.014 kg x 1350 mg/kg = 18.9 mg New Research I had the good fortune of running across a farm page called Red Horse Valley LLC. Mrs. Kathy Winters shared some astounding information about chronic copper toxicity in her herd - she's helped me personally so much. I will summarize here, but please do go check out her page and her in-progress research https://www.facebook.com/RedHorseValley and https://www.gofundme.com/f/6ktxc4o. By donating $25 or more to the Go Fund Me, you can obtain the most recent copy of her paper "In Search of Balance: a Nigerian Dwarf Breeder's Experience with Chronic Copper Accumulation." I highly recommend it! It is a worthy cause and the paper is absolutely full of fascinating information.
Multiple losses and subsequent necropsies confirmed copper toxicosis in the Red Horse Valley LLC herd. Water, forage, concentrates, mineral, and hay were all analyzed. An imbalance in zinc and copper was found in the second mineral she had offered for 18 months. “Despite the absolute DMI of copper of <40ppm (as recommended by the NRC, 2007) when using either mineral supplement, losses documented to be caused by chronic copper toxicosis became evident when the relative overall concentration of zinc to copper consumed was decreased from >5:1 down to <3:1 with the introduction of the 2nd mineral supplement (on total DMI basis)” (20). The paper on her experience is fascinating, an absolute wealth of information (and yes, properly sourced!) but what I found the most fascinating was the symptoms of confirmed copper toxicity. Goats displayed poor coats, especially lightening or reddening of coat colors, “fishtail,” hair loss, and thinning or breaking hair. The very symptoms we’ve learned are sure signs of copper deficiency! These symptoms improved after the removal of controllable copper sources and with copper chelation therapy – a therapy that removes accumulated copper from the tissues.
Below, you can see photos provided by Red Horse Valley LLC. The buck in the first picture showed reddening of his black coat and balding tail tip. "Also evident is the shaved right side which was done just prior to ultrasound guided liver biopsy on 2/21/2019. Results indicate, contrary to the myth that balding tail tips and reddening of the coat as symptoms of copper deficiency, he does NOT have copper deficiency (indeed, results are bordering on elevated levels of over 400ppm dry weight)" (20). The bottom photos are before (left) and after (right) photos of a buck that received copper chelation therapy.
I believe Mrs. Winters says it best – “It is much preferred, and I feel should henceforth be referred as symptoms of mineral or nutritional imbalance in order to prevent the rampant supplementation of copper for every sign of poor coat condition without proper diagnosis” (20). The herd was receiving too much copper which in turn caused secondary zinc deficiencies – many goats had skin issues as well as coat issues. As Mrs. Winters points out in her paper, many nutrition studies in goats are very short term yet “The chronic copper accumulation phase can be lengthy and without outwards symptoms” and “The absolute amount of copper in the diet on its own is insufficient to determine long-term safety” (20). I think this is something very important for breeders to consider!
A Final Note
At this time, I want to point out that no matter who your mentors or learning sources are, no one should make a copper recommendations without asking about copper antagonists in your forage, concentrates, mineral, hay, and water, as well as about the copper content of your forage, concentrates, mineral, hay, and water. Better yet, they should ask about tissue analysis! Blanket statements like “Goats should also have a free choice mixed mineral available, and it should have around 1500ppm copper sulfate” with no other explanation should be a red flag. Too many folks, especially popular laymen on the internet, are too quick to present you with a number and no caveats!
I hope more research is conducted and soon. It seems to be that too often, increasing copper is a cure-all. I hope more breeders utilize tissue testing and forage, hay, and water testing. Read those feed and mineral labels. Read the ingredients in supplements. Scour the internet (Google Scholar!) and textbooks for new research, especially research from scholarly sources. Finally, I hope these articles have helped. I am sincerely grateful for all the help I've received and for all those folks who have been interested in learning! I am honestly not sure what article will be next, perhaps a look at minerals that affect hair coat...
Sources for Part Two -
1. Vázquez-Armijo, José & Rubio, Rolando & A.Z.M., Salem, & López, Daniel & Tinoco, J. & González-Reyna, Arnoldo & Pescador Salas, Nazario & Vara, Ignacio Arturo. (2011). Trace elements in sheep and goats reproduction: A review. Tropical and Subtropical Agroecosystems. 14. 1 - 13. https://www.researchgate.net/publication/262681507_Trace_elements_in_sheep_and_goats_reproduction_A_review
2. Smith, M., Sherman, D. and Smith., 2009. Goat Medicine. 2nd ed. Somerset: Wiley.
3. Baird, N. (Nickie), and Pugh, David G.. Sheep & Goat Medicine - E-Book. United Kingdom, Elsevier Health Sciences, 2012.
4. Hefnawy, Abd Elghany, and Heba M. El-khaiat. “Copper and Animal Health: Importance, Maternal Fetal, Immunity and DNA Relationship, Deficiency and Toxicity.” IJAVMS, vol. 9, no. 5, 2015, https://pdfs.semanticscholar.org/1481/8430e40f378646f9d819c73303a61c929769.pdf.
5. Maas, John. “Copper Deficiency and Toxicity in Ruminants (Proceedings).” DVM 360, July 2009, https://www.dvm360.com/view/copper-deficiency-and-toxicity-ruminants-proceedings.
6. Jerry W. Spears, Trace Mineral Bioavailability in Ruminants, The Journal of Nutrition, Volume 133, Issue 5, May 2003, Pages 1506S–1509S, https://doi.org/10.1093/jn/133.5.1506S
7. Bozynski, Chantelle C., et al. “Copper Toxicosis with Hemolysis and Hemoglobinuric Nephrosis in Three Adult Boer Goats.” Journal of Veterinary Diagnostic Investigation, vol. 21, no. 3, 2009, pp. 395–400., doi:10.1177/104063870902100319
8. Cornish, Jennifer, et al. “Copper Toxicosis in a Dairy Goat Herd.” Journal of the American Veterinary Medical Association, vol. 231, no. 4, 2007, pp. 586–589.
9. Hart, Steve. “Goat Nutrition Copper.” Goats, 14 Aug. 2019,
10. Banton, Marcy I, et al. Enzootic Ataxia in Louisiana Goat Kids - SAGE Journals goats.extension.org/goat-nutrition-copper/.. 1990,
11. Metre, Dan Van. “Copper Poisoning in Small Ruminants.” Colorado State University Extension, veterinaryextension.colostate.edu/menu2/sm%20rum/Copper%20Poisoning%20vm-knight-engle.pdf.
12. Blakley, Barry R. “Overview of Copper Poisoning - Toxicology.” Merck Veterinary Manual, Merck Veterinary Manual, Sept. 2013, www.merckvetmanual.com/toxicology/copper-poisoning/overview-of-copper-poisoning.
13. Cregar, Laura C, et al. “Copper Toxicosis in a Boer Goat.” Veterinary Clinical Pathology, U.S. National Library of Medicine, 2012, pubmed.ncbi.nlm.nih.gov/23121408/.
14. Suttle, N F. “The Interactions Between Copper, Molybdenum, and Sulphur in Ruminant Nutrition.” Annual Reviews, 1991, www.annualreviews.org/doi/abs/10.1146/annurev.nu.11.070191.001005.
15. David B. Smith, William F. Cannon. “Geochemical and Mineralogical Maps, with Interpretation, for Soils of the Conterminous United States.” USGS Publications Warehouse, 2017, pubs.usgs.gov/sir/2017/5118/sir20175118_element.php?el=42.
16. “Goat Nutrition Molybdenum.” Goats Extension, 14 Aug. 2019, goats.extension.org/goat-nutrition-molybdenum/.
17. German, Dave, et al. “Interpretation of Water Analysis for Livestock Suitability.” ERAMS Online, erams.com/static/wqtool/PDFs/Interpretation of Water Analysis for Livestock Suitability.pdf.
18. Haenlein, G.F.W. “Mineral Nutrition of Goats.” Journal of Dairy Science, www.journalofdairyscience.org/article/S0022-0302(80)83133-X/pdf.
19. Rasby, Rick J. et al. “Minerals and Vitamins for Beef Cows.” Nebraska Extension - University of Nebraska - Lincoln, 2011, extensionpublications.unl.edu/assets/pdf/ec288.pdf.
20. Winters, Katherine A. “In Search of Balance: A Nigerian Dwarf Breeder's Experience with Chronic Copper Accumulation.” 2019, pp. 1–35.