This looks like a metatarsal. If the bone is about 25 cm (10 in) long, I say this is cow.
The bone is only 11cm long and big end 2.5cm long.
I have just measured a roe deer at 13cm long and 2.2cm wide at the end, this makes deer metatarsus longer and thinner. I don't have a sheep to measure but that would be my best guess now that we know the size.
Thanks, John! It seems that it's a sheep metatarsal, as you said. Here is a comparison with one of our specimens: