Excess protein fed to chickens is not good...excess would be over 25% or so for long periods of time. Feathers consist of about 85% to 90% protein. And during a hard molt, it is hard to get enough protein, energy and other essential vitamins, minerals to grow all these feathers without extra protein. So extra during molting will only do them good. The problem with plant proteins are that they don't contain enough fatty acids and amino acids to break down the protein to turn it into usable proteins. Meat naturally contains many fatty acids and amino acids to break it down in a usable form.
I was told that when feeding things like meat, to only feed once a day what they can clean up in 10 mins. I am only giving my birds about a 1/2 ounce a day each and it has made a huge difference in their feather growth and the fact that they are not eating any more feathers means their protein needs must be being met a bit better than they were before feeding meat.
I am very interested in this concept, so have been investigating. Forgive me for a long-ish post.
I have no fixed opinion on this topic as I'm still in the information-gathering phase, but I'm leaning toward a higher-percentage of protein than is generally recommend for laying birds with the idea that I can adjust the protein percentage with whole grains. I'm going to repeat some things I've either read and hope I can do that without seeming argumentative or judgmental ... I'm really just trying to get a grip on the information so I can do right by my birds. (And for full disclosure, I've been feeding my laying flock commercial layer pellets that are about 16% protein with additional calcium on the side, but also put out some all-purpose poultry food that I believe is 20% protein as I've always got chicks around ... I'm feeding the mature turkeys the all-purpose poultry food even though the feeding charts indicate I could be feeding them a lot less protein at this stage (this is just because we've been lazy about switching over to something else) ... the ducks get some & some. HOWEVER ... We're switching everyone over to the all-purpose flock ration at 19-20% protein, with the calcium on the side AND we do give them some scratch grains which are about 9% protein ... all the birds have forage ... and now that they're molting I occasionally supplement with either scrambled eggs or buttermilk-soaked cat kibble ... and I'm considering offering cooked meat/offal) ...
... SO ...
I've spoken to a custom organic feed mill about making an all-purpose high-protein & nutrient/pro&prebiotic poultry pellet that I could "cut" with whole grains to achieve different percentages of protein for different types/ages of birds (turkeys, chickens, ducks ... from hatch on up) -- I could grow some of the whole grains I cut that with, or get the grains right off the combine, so this could be a big savings if the base pellet is affordable. Among many, many considerations for implementing that type of feeding plan for a diverse flock, we spoke about my concern over offering any bird too much protein, and I quoted various things I've read here at BYC that "too much protein is not good." I was told the "too much protein" idea is a "myth," their word not mine, and that excess protein is excreted without damaging the birds organs or confusing the bird's growth. So I've been trying to track down the science on this idea ... the general science of protein percentages and poultry health.
I also spoke with a nutrition consultant for a larger feed company, and was advised that their all purpose poultry ration at 19% would be a better choice for my situation than any of their higher-protein options (mostly rations for starting meat birds). I asked, but was not told, if this was because of the "better" supplements in the 19% food compared to the higher percentage foods. I have a suspicion the higher-protein-percentage meat bird starter rations don't have as many added nutrients because those birds aren't expected to live very long -- phrased differently, my suspicion is that meat bird feeds aren't designed for long-term health maintenance, but that's just a hunch.
As I understand it and someone else has written about previously in this thread, the goal of industrial poultry keeping is to feed with the best economy ... so the expensive things like proteins (and added nutrients) are offered at the lowest useful percentages to achieve an acceptable level of health at various stages in life or for different types of flocks (layers vs. breeders vs. meaties, for example). It's about optimizing efficiency over a limited life-span of an industrial bird, not about optimizing long-term health. So these "feed efficiency" type charts are what I find when I research. There is quite a tradition of these charts. So far they're all I can find.
Converse to the "too much protein is not good" warning I've read several times here at BYC, over in the Heritage thread I read a recommendation to offer the special LF Heritage birds a very high percentage feed at all times ... if I remember correctly it was somewhere between 24% & 30% ... the highest protein poultry feed I'm familiar with is turkey starter or game bird feed at 28-30% protein. I'm feeling too lazy to go check that recommendation. Someone else recommends feeding pullets and cockerels of large heritage birds a very low protein feed ... I think it was 9%, which is more like scratch grains ... because they want their big birds to grow nice and slow so they live longer.
Big Sigh. Obviously the conversation about protein percentages extends beyond molting, but a thread on molting is as good a place to ask these questions (again) as any.
When I feed the scrambled egg or buttermilk cat food "treats," I can barely put the containers on the ground before the treats are gone. I can't fathom a quantity that could last 10 whole minutes. I'm sure they could inhale a lot. I use several containers with the hope that maybe everyone gets a chance.