Eradication and Accreditation are two different things
'BVD virus (BVDV) is closely related to the viruses that cause classical swine fever in pigs and border disease in sheep. In theory, sheep and deer, can be a source of infection for cattle, although sheep are at greater risk from cattle than vice versa. There are other issues with L hardjo as well. L. Hardjo has been recovered from the urine of sheep, and one study has shown that cattle herds are more likely to be infected with leptospirosis if sheep are present on the farm. It is recommended that contact between cattle and sheep is kept to a minimum. As leptospira do not tolerate drying or exposure to sunlight, a rest period of two months after grazing by sheep or infected animals should make pasture safe for uninfected animals.'
The CHeCS rules are mandatory for herds in the Accreditation programmes.
16. Co-grazing with sheep or other domestic ruminants or camelids: Although not a mandatory requirement, it is strongly recommended that, wherever possible cattle and sheep do not graze together.
I don't have to sell my sheep so will not be parting with them for a silly price but on the other hand if one is going to enter into the spirit of Accreditation then I take the view that you should follow the scheme's recommendations - as it is costing me an arm and a leg. Although I will be taking up the 3 metre boundary bit with our vet who seems to want to 'gold plate' everything.