I just had a standard size sex link roaster kill a silkie hen breeding her. Just too rough. Separated the head from the neck. Stupid, stupid roster. Just be careful he didn't even try to pick on her. Zita
Large fowl with other large fowl shouldn't be a problem. I had a relatively large mutt, not JG giant, but over 10lbs, and his favorite girl was a 4lb all feathers leghorn. I also had free raining silkies but none of the standards belived they were birds and they did their own thing with their own rooster. Not even the head rooster bothered fought or even looked at the silkie roosters.