If your dogs are good hunting dogs that posses the traits that you want in a hunting dog.. and are good producers on top of that... why in the hell would you chase some old wives tale that hunting a bred bitch makes hunting pups?
Shouldn't the dogs being bred be able to produce dogs that hunt just as well without doing something that was thought up before we had penecillin?
If you want one, some, or all of the pups to detatch from the uterine wall, die prematurely inside of the bitch, and cause a SEVERE infection that can kill a bitch that you thought was good enough to breed in the first place... then by all means.. hunt a bred bitch.
Genetics, heredity, a good understand of geneaology, and productive/educated breeding practices are the key factors in producing good hunting dogs, in my mind.. besides using proven stock.... not the theory that a molecular amount of seretonin is going to affect a dogs basic evolutionary desire to track and persue game. While its an interesting thought how some of sintroduced traits become fixed within a line of dogs... I think its more complex than things like the notion of hunting a bred bitch will make that much more of a hunting litter...
While we're comparing apples to oranges... If these notions were true.. You'd see bulldoggers breeding bitches and then matching them to produce better fighting pups.. and that is not at all the case.. Some of the best bulldogs alive came from bitches who wouldnt fight to defend themselves a day in their lives!