we've just started with pigs and sheep and have read that copper sulphate added to pig feed is poisonous to sheep. Does anyone know how much of the copper makes it into the ground and how long it will stay there and / or the grazing, ie, how long after keeping pigs on a patch of land before the sheep can move in?
On a similar note, the duck feed we use also has added copper, though not as much as the pig feed (12mg / kg vs 150mg / kg). Would this lower concentration spread over a much larger area also pose a risk?
Any help gratefully received,
As for how long before they can graze etc, I honestly don't know but a feed manufacturer will be able to give you good advice.
I see that you live in France. Do you know what your current copper level is in the soil? If it is already high then extra care would probably be needed. Also if other metal levels (ie iron etc) are high in the ground then the copper will be locked up to an extent.
The weather will play a part in how much will get into the grass. A dry summer with slow growing grass will take up more copper & pass it on to the sheep. A soaking summer like we've got used to over here will not only wash a good amount out of the ground but the grass will grow quicker and uptake far less trace elements including copper.
I would seek the advice of a feed manufacturer, preferably one local to you if you're not aware of the copper status in your ground or have a word with a few livestock farmers close to you who might be able to give you a 'heads up' on soil status.
A lot of cattle feeds/buckets contain up to around 3000mg/kg copper of which approx 75%+ will be passed out in the dung. This dung spread on sheep pasture doesn't seem to cause the sheep problems over here but certainly worth checking as I assume the pig pooh will be in a concentrated area.
thanks for the reply.
The land hasn't been used for pigs before, I'm just thinking ahead. The sheep are black-faced and (lucky me) I'm collecting the pig pooh for the compost heap. So, from what you've said perhaps not the initial problem I thought, will keep searching and maybe leave the sheep out of the area for a year after the pigs have moved and mow and remove the grass cuttings.