Copper - What's the big deal?

My blog has strayed away from farming for a bit. I've been helping a woman with her dairy goats and it has brought back my focus - still no farm of our own though! I borrowed a few dairy goat books from her and a topic I've been meaning to research has come up - Copper. I've heard/read it many times, sheep can't handle copper, it's toxic to them. However, many of the other animals we want to have need copper. What to do since we want them all to share the same space?

It is true that sheep can get copper toxicity from too much copper but they can handle some. So, what is the acceptable level? According to Susan Schoenian, a Sheep & Goat Specialist at the University of Maryland's Western Maryland Research & Education Center and an affiliated faculty member of the Department of Animal and Avian Sciences at the University of Maryland College Park, Generally, sheep require about 5 ppm (parts per million or mg/kg) of Cu in their total diet. Toxicity can occur at levels above 25 ppm. (http://www.sheepandgoat.com/articles/coppertox.html)

So the next obvious question became, what levels do all the other animals need for their minimum nutritional needs to be met? You would think this would be an easy to find answer, and yes I did eventually find it, but not before coming across some other information. It seems that many swine farmers supplement their pigs heavily with copper because research has shown it improves their growth rate. Apparently 200-250 mg/kg is a common level however there is some research that suggests 100-150 mg/kg provides just as much but obviously at a lower cost. But, and this is an important but, should we really be supplementing that high when the level they actually need is 10-25 times less? What is the environmental impact of all that extra copper? What about all that extra copper in the foods we eat? I was fortunate to find a great article that discusses these issues and outlines required copper levels for many animals. The article is from the European Commission, Health and Consumer Protection Directorate-general,(http://ec.europa.eu/food/fs/sc/scan/out115_en.pdf).

Here are the levels, as outlined in the document mentioned above. Please note that copper, as with many minerals and vitamins, can interact with other minerals and vitamins that can either aid or hamper it's absorption. In addition, their bioavailability can be different depending on the form of copper used and the amount required can change based on stage of life of the animal.

Pigs 3-10 mg/kg
Cows 9-10 mg/kg
Sheep & Goats 5-11 mg/kg
Chickens & other avian species 4-8 mg/kg
Turkeys 6-15 mg/kg

The thing with sheep, as mentioned above, is that they have a rather narrow window before the copper levels can lead to toxicity but they should be fine up to 25 mg/kg. Since most of the species need between 3-15 mg/kg the sheep should be just fine.

Next I decided to look at food sources and their copper levels. Again taken from the above mentioned article, is this handy list. Please note that the levels can vary depending on the region the food is grown in. If the soil is deficient in copper, then the crops grown will also be deficient. I have included the entire list for those who may be interested.

Alfalfa hay 7.3
Alfalfa meal CP=12 20% 6-7
Barley 3.5-7
Barley dist. grains 37
Brewer's grain 20-22
Brewer's yeast 25-57
Citrus pulp dried 4.3-6
Cotton seed 14
Cotton, dehulled solvent 3.2-18
Fish meal 5.6-10
Grass hay 9
Horse beans 10.7-13
Linseed 12-16
Linseed solv.extr 18
Lupins 6
Maize 1.9-3.3
Maize dist. grains 45-75
Maize dist. sol. dehyd. 17-72
Maize germ meal 7-12
Maize gluten feed, meal 6-31
Maize silage 7.6
Oats 2.8-5
Rapeseed, solv. Extr. 5-7
Rapeseed whole 7
Rye 4-6
Skimmed milk 0.9-6.5
Sorghum 2.7-10
Soybean meal 44 14-20
Soybean meal 50 15-18
Soybean whole 12-15
Straw Barley 1.7-5
Straw Wheat 7
Sugar Beet Pulps 10
Sugar molasses 8.4-12
Sunflower 25
Sunflower Dehulled 28
Torula yeast 15
Triticale 3.7-10
Wheat bran 10-30
Wheat hard, soft 4.2-8
Wheat middlings 5.8-9
Wheat middlings 12-13
Whole milk powder 1.3

It looks like grass hay may provide the level we need for most of the animals we are working with, which is great since we want a grass fed only system for the ruminants. However, it is our intention to provide seeds, nuts, fruits and vegetables to the animals so they can get the vitamins they need for good nutrition, with the non-ruminants getting a proportionately larger amount. Sunflower (25 mg/kg) is one of the ones we plan to use so will need to be aware of the high level of copper. It is still within the acceptable level for sheep, although the maximum. I will need to do more research as I go along so I can be sure of a balanced diet for the animals, but at least the copper 'problem' is solved.