Copper is a trace mineral essential to the well being of horses. As we strive to provide our horses with a good diet, we add supplements to complement the lack of nutrients from depleted paddocks or diets that do not suffice in regards to minerals and vitamins. Of course, we want to give our horses the best so we look for natural sources of copper.I have heard and read so many times that Rosehip is a great source of copper and a couple of tablespoons a day (50 g) will provide enough copper to meet a 500 kg horse’s requirements. Other people swear by Copper Sulphate (Bluestone) as the best source and happily puts a teaspoon (5 g) of it in their horse’s feed. So where is the truth? Is Rosehip the best herbal source of copper? Before one can answer that, one must find out how much copper does a horse need per day. According to NRC 2007 Nutrient Requirements of Horses, a 500 kg mature horse needs 100 mg of copper a day for maintenance. This is only an estimate as it will depend on the horse’s level of activity and his colour. Apparently, dark horses, including liver chestnut ones, seem to require higher levels of copper for their pigmentation. Copper is required for development of bone, joint cartilage, elastic connective tissue, uptake and utilisation of iron, and copper containing metabolic and tissue anti-inflammatory enzymes **.
Feed sources of copper available to horses
Common feed sources
- Lucerne Hay 9-16mg/kg **
- Corn 3.4mg/kg **
- Oats 12.6mg/kg **
- Barley 5.3mg/kg **
- Copper sulfate (Bluestone) 1300mg/5mL **
- Copper sulfate (Bluestone) 1250mg/5g
- Copper carbonate 2800mg/5mL **
- Rosehip 0.1 mg/100g *
- Wheat bran 1 mg/100g *
- Millet 1mg/100g *
- Rice bran 0.7mg/100g *
- Seaweed (dried) 6.1mg/100g *
- Sunflower seeds 1.8mg/100g *
As you can see, Bluestone is the highest source as it contains approximately 25% of copper. So 5 g of Bluestone everyday in your horse’s feed is a lot of copper!
Apparently, horses, unlike ruminants, can sustain very high levels of copper. However, 5 g is 10 times over their requirements. So for the pro Bluestone, maybe 1/2 gram of it will be enough as one must take into consideration it would not be the sole feed source of copper. A study was done with ponies who strive on a land where the copper level was so high it killed lambs. It is unknown how much copper a horse can tolerate but the maximum amount recommended is 800 mg/kg diet.
As for Rosehips, well, the numbers speak for themselves. Rosehip has other advantages that are of benefit to horses, but as a source of copper, it fails miserably unless you are feeding your horses kilos of it a day! *
More on copper can be found at Copper Alliance
* Sources: https://nutritiondata.self.com/
** Feeding Horses in Australia, John Kohnke, 1999