[quote=NickP]so all lines produce a similar dog :?:[/quote] This 2 new line will be bear soon .(Filas x DDbordeaux x APBT(tosa). Fila x Amercian Bulldog x APBT(tosa)) Similar dogs are produce if my theory works and if i have luck to have a large offspring to select the best puppy... The aim is to select in the offspring the best dog that fit in our standard. With 3 diferent lines but all 3 inherated by the same parent dogs (Tornado) and (Lama) i will do a narrow cross/back cross together breding out in the F3... Fila x Bullmastiff x APBT(tosa). x Filas x DDbordeaux x APBT(tosa) Fila x Bullmastiff x APBT(tosa) x Fila x American Bulldog x APBT(tosa). Fila x APBT(tosa) x Fila x American Bulldog x APBT(tosa). Fila x APBT(tosa) xFilas x DDbordeaux x APBT(tosa) ...the American Bulldog and DDbordeaux and mantain the vigor.