Some of the wording on various feed products can be quite amusing. Purina,
Manna Pro, etc. have multiple granaries throughout the country, so packaging is ordered in bulk, probably from China. The language(s) used on the instructions are not always translated perfectly, so a word here or there can be confusing. Not feeding oyster shell plainly, is a good example of that. What they are trying to convey, is not to feed oyster shell in lieu of feed. Feed is required, not just oyster shell.
Have any of you ever bought something like
Manna Pro Garden Delights, and given them as a treat? There are quite a few ingredients. Dried peas, dried carrot flakes, raisins, peanuts, to name a few. Each chicken will hunt for the things they like best, avoiding the things they don't like. One will go picking out all the carrot chunks, avoiding the other ingredients in the mix. Another will pick out all the peanuts, another will search out, and eat all the peas, and so on. When they're satisfied they've eaten all of whatever their favorite is, then they move on to the less favorite ingredients. This is not a plug for buying treats, but a good example of how chickens tend to eat. Whether to treat, or not is a personal decision, but the rule of thumb is: Don't give treats too often. They can only eat so much daily, and it's best they get their fill of optimum nutrition, which treats don't provide.
We all agree that scratch alone is NOT nutritionally adequate.
Feeding a good layer feed tends to be nutritionally adequate, for the most part, including calcium. There will be times that the hens will want/need a little extra calcium. Putting a little oyster shell in a little container, or just a little handful on the ground apart from the feeder gives them the option. For the most part, they should not need it, and won't touch it, but once in awhile they will need a little extra boost of calcium. It does not have to be mixed with the feed. Remember how selective they are with the treats. They will only eat it, if and when they need it, and only the ones that need it will eat it, so it tends to be wasteful to mix it with the feed. The rooster(s) normally won't touch it either.
Some people like to feed using a flock raiser feed, instead of layer feed. That is good, but there is not as much calcium in the flock raiser, so the hens will usually need a little extra calcium to maintain a good protein/calcium balance.
Due to the constraints of the granary(ies) in my area, the feed(s) I would like to use is not available to me. For laying hens, I use a layer feed. I use a little bit of Calf-Manna, which is very high in excellent animal protein, as an occasional treat, making sure all of them get a little, not just the roosters, and hens that are higher in the pecking order. To maintain the protein/calcium balance, oyster shell is free choice. They will eat it, only if they need it.
During molt, when they need both extra protein, and calcium, I tend to up the Calf-Manna to a small amount on a daily basis, instead of the occasional treat, and keep a little more oyster shell available, along with their normal feed. They don't tend to go through as hard a molt when I do this, they resume egg laying more quickly, and grow feathers back in more rapidly. Towards the end of their molt, I resume feeding as usual.
