and the bitch has just had puppies, we are keeping the male dog seperate from her while she nurses the puppies, how long should he be kept away from her?
I would keep him away until they are at least six weeks as you dont know how he will react, but having said that a friend of mine's male dogs always go in and wash the puppies to help with mom, irrespective of whether they are the father or not. But another friends male dog, just doesnt 'do' puppies until they are 'of age'!!
I'd leave it to the bitch to decide - let him near to them on a lead and see her reaction - if she is ready to take his face off then take him away and try again another time. If she doesn't mind then provided you supervise the contact they should be ok. One of my males loves puppies and lets them climb over him.