If you’re interested in caponizing, look at the capon thread in the meat bird forum. You can also poulardize if you find you have more females than you need, and that reportedly produces the tenderest meat of all.
From what I’ve read, these procedures promote a much higher percentage of fat storage in the muscles (and I expect, in the normal fat pads as well). One can then keep the birds as long as desired without fear of them becoming tough and stringy. A benefit to this being that freezer storage space needs will decrease, since there’s no need to rush to butchering before the cockerel reaches sexual maturity.
People object to the pain caused by doing this surgical procedure without anesthesia, but it’s my understanding that birds do not tolerate any known types of anesthesia well at all. (One person suggested that lavender essential oil has been known to induce a deep sleep in chickens, but did not specify which type of lavender oil.) While some birds do react with an apparent pain response, this appears to be rare. The pain response (in the rare instance that one is apparent) comes from the incision, not from the probing about inside, as there are no nerve endings on the internal organs and viscera.
The greatest cause of distress is usually reported to be the restraints and/or the extended fast required to empty the intestinal tract (which is in very close proximity to the reproductive organs) in order to improve visibility and avoid breach of the intestines. Following a successful procedure the typical bird immediately turns his attention to food and drink. In most cases suturing is not needed as the skin is displaced from the incision site prior to the initial cut. The skin itself provides coverage to the surgical site.
Because the incision does communicate with the lungs, skin puff, wherein the skin becomes inflated by air post-op, sometimes occurs. The remedy for this is to “deflate” the patient via a puncture or small incision through the skin. Skin puff is much more common when the skin has been sutured or glued together.
All the people who described their experiences in learning to caponize lost at least a bird or three. My thoughts on this are that the birds are (in a meat bird operation) destined to the knife in any case and a death via bleeding out during an unsuccessful caponization is in all probability not a worse death than that experienced in the slaughtering process. Birds do not bleed out instantaneously. It reportedly takes a human being about five minutes to bleed out. I haven’t timed it, but it seems to me that chickens are not faster than that. A nicked internal artery (the usual cause of death during the procedure) cannot possibly be more distressing than having the carotid arteries opened whilst hanging upside-down.
An experienced operator can caponize a one to two pound bird (the optimal size) inside a minute or two. Older birds take longer and are much higher risk & more difficult to do. The main reason to caponize a mature cock would be to save a pet boy from the natural consequences of his crowing and aggression. When the procedure is successful, the mature roo will often lose his aggression and cease or greatly reduce the frequency and/or volume of his crowing—but NOT always.
Just my summation of some of the things I learned from reading the caponizing thread. Hopefully it’s helpful... reading through the whole thread is well worthwhile.