I have noticed a couple oft does have yellow streaks down there backs. I have a young buck in with them. Could this be him doing his job? I haven't noticed him trying to breed them but I'm not around through out the day. It looks like urine stains.
Unless the buck is considerably larger than the does, urine stains would likely be coming from his front hooves as he mounts but it is more likely to be dirt or manure from his hooves as he tries.
Do you want these does bred?