I have a composting worm farm and would like a definitive answer, as what I've read so far is confusing.
When adding scraps of dog bones from beef or lamb, or inedible (for small dog breeds) chicken bones, what can I add to maintain the proper carbon-nitrogen ratio in this hot bed of worm activity?
I'm not sure if the bones still contain meat, so I'll answer for both.
Meat
It's certainly possible to add meat to your worm farm, but many people warn against this because of the risk of attracting vermin and the possible bad smell of decaying meat. To reduce these risks it's best to use a closed worm bin so critters can't enter, add only a few small pieces of meat at a time and bury the meat pieces under other material. Alternatively you can pre-process food left-overs in a bokashi bin first.
Bones
You could also add bones to a worm bin or compost heap, but without any treatment bones won't decompose in any reasonable amount of time, so there is little point to do so. If you have the tools, you could create your own bone meal, but bone meal can be applied directly to one's garden so again there is not much point to add it to your worm farm.
General guidelines
When adding food to a worm bin there is always a chance that the worms (initially) won't like the food because it's not yet decaying or because it's too sour, too moist, too greasy, etc. Usually the problem resolves itself after a while when microbes and fungi have affected the food and it starts decaying. To speed-up decomposition it's best to chop up food in small pieces.
You want to add food to only a part of your worm farm at a time, so the worms can escape to safer places if necessary. This is especially important when adding nitrogen-rich foods that will warm up the food as it decomposes. You also want to keep the carbon-nitrogen ratio (C:N ratio for short) in balance to prevent bad smells and keep decomposition going. This means that when you add meat or bone meal (both of which are nitrogen-rich) you also need to add 'brown' (carbon-rich) materials. All materials that have a higher ratio than 30:1 in this answer count as a brown material.
You can alternatively make bone broth out of your bones. After several hours of boiling them, you’ll have a mineral and nutrient-rich broth in addition to significantly softer bones that are easier to decompose. Some people put them through two rounds of boiling at which point the bones crumble in your hand (which when salted become chewy calcium snacks for both canine and children). The crumbled bone are now easily compost-able.
Source: Nourishing Traditions
*If you choose the bone broth route, I recommend roasting your bones first so that the future broth's aroma is simply scrumptious. Bone broth is the chefs' favorite as the base for many soulful soups.
