Others have offered very good explanations, I would just elaborate slightly, that this is a basic genetic breeding principle for almost anything you choose to breed (animals, plants etc.).
Its a true numbers game. The real key to any breeding program is good breeding stock of stable genetic speciemens (ie, very true breeding birds, with little to no variance from the original parents) Once you have a male, female selected, its just a matter of growing out MANY offsprings of the two parents, then selecting based on what characteristics you are looking for (fast growers, large breast, etc). The real key here is LARGE numbers, you would really need several thousand offsprings to choose from, selecting maybe 25 out of several thousand(these would be your F1 hybrids) first generation, then you would back cross over and over each time doing detailed selection for the characteristics that you are seeking. The real trick is to develop a "stable" cross that breeds true each time. This is a very long process, and requires LARGE numbers of offsprings to get true good selections from each generation, you are looking for a needle in a haystack so to speak. You are selecting for a specefic gennetic charateristic, and then trying to bring out that characteristic over and over without other less desireable characteristic showing up in the next generation. Its a fun project, but no home breeder has the space, time, money, or experience to come even close to breeding something like the cornish Xs you get from large scale breeders.
Its a true numbers game. The real key to any breeding program is good breeding stock of stable genetic speciemens (ie, very true breeding birds, with little to no variance from the original parents) Once you have a male, female selected, its just a matter of growing out MANY offsprings of the two parents, then selecting based on what characteristics you are looking for (fast growers, large breast, etc). The real key here is LARGE numbers, you would really need several thousand offsprings to choose from, selecting maybe 25 out of several thousand(these would be your F1 hybrids) first generation, then you would back cross over and over each time doing detailed selection for the characteristics that you are seeking. The real trick is to develop a "stable" cross that breeds true each time. This is a very long process, and requires LARGE numbers of offsprings to get true good selections from each generation, you are looking for a needle in a haystack so to speak. You are selecting for a specefic gennetic charateristic, and then trying to bring out that characteristic over and over without other less desireable characteristic showing up in the next generation. Its a fun project, but no home breeder has the space, time, money, or experience to come even close to breeding something like the cornish Xs you get from large scale breeders.
