If one was to use chicken pieces as a dietery supliment for say carpet pythons , what pieces would provide the most nutritional benifit to the animal ? For example what would have the most calcium and protein , which would have the most fat ? As its only an occasional supliment , dose it matter anyway ? All opinions welcome.
As long as there's any bone it doesn't matter how much; snakes get way more calcium than they need. You could give some meals with no calcium ie no bones (no, if it's just an occasional supplement it doesn't matter). I've done this for many consecutive feeds in some cases, never with any noticeable problem.
Protein comes primarily from the muscle (meat) and partly from the marrow (inside bones) and skin.
Fatty cuts of meat have more fat, skin has more fat than meat, marrow also contains fat.
Herpers and western people are obsessed with fat in a stupid way, and I've noticed the fat myths creeping into Asia over the last 3 years or so, which has coincided with a dramatic increase in the proportion of people becoming overweight. You don't get fat because you eat too much fat, you get fat because you eat too many calories. As an example, cows get big and fat, they're loaded with fat, you can see it in beef. Beef fat is a thing. Cows eat basically nothing but grass which is pretty much fat free. As another example, when I was first in Thailand about 6 years ago all the women were stick thin and I found it amusing to see them gobbling down meals with big chunks of pig fat, while all the fat western women back in Australia were paranoid about touching fat. Over the last few years, there have been three big changes I've seen: (1) fat shaming went from being completely normal and very common to being taboo like it is in the west, (2) western 'don't eat fat' myths came in, and (3) Fat people, particularly women, went from being nowhere to being everywhere. Don't be scared of fat, especially in something like snakes. As long as you (or a snake) gets all the macro and micro nutrients it needs, it doesn't particularly matter where the rest of them come from.
I love to analyse things to pieces because I'm a nerd, but really, the bottom line is that if you care for the sake of caring about the snake, just feed them rats and mice. If you're using chicken because you're cheap, just use whatever cut of chicken is convenient.
I've also fed snakes various meat including beef, roadkill of all sorts, etc etc. It's a good idea to avoid anything you're not sure about, and freeze anything which potentially has parasites.