the 20% protein feed. This is a high level of protein. No feed in my country contains that much protein. It varies from 14% - almost 20% for chicks. And what level is best, depends on what kind of chickens you have (chicks, heritage breeds, mixed flock, broilers for meat or commercial laying hens) and how/where they live too.
20% is not high. I've often fed 24% with no ill effects.
What does protein do for chickens?
Look at their feathers. Those are constructed from protein. During growth from a chick, they have to grow a whole new set 5-6 times. All chickens share the characteristic of protein hungry feathers.
Now one might say "These aren't show chickens, I don't care"... but it's a metric for health because, if protein is lacking it can affect the internal organs / connective tissue. Not readily apparent, it may show up as sudden death from heart attacks, as intolerance to heat or cold, a lower immune system, and the list goes on. It has many potential damages because the need for protein in the body is so extensive. Feathers are the canary in the coal mine.
Can chickens not in the peak of health still serve human needs? Yes. It's not ideal, and not what I'm ever going to recommend, but yes they can support human needs without having their own fully met.
Earlier in my keeping journey, I fed my chickens a basic layer. For years they looked "fine" to me. But I had never seen a chicken with healthy feathers to compare. To me, the dull appearance of a wide variety of breeds that we kept looked totally normal. Through the season their feathers would get damaged easily and I didn't know that was a symptom of a bigger issue.
Fast forward to when I tried a higher protein feed. I was raising a pure breed I had wanted for a while and the "extra" protein of 22% vs the old 18% chick starter was just to hedge my bets.
I could not
believe how much better their feathers looked. Pretty soon all our breeds were on 20% as a minimum, and after they molted I was struck with guilt. I truly felt like I had been a miserly keeper, and not done my proper research.
That's my story and why I believe in and tout protein. Like many, I got into the hobby for the welfare of the birds.
I understand that in many countries it is hard to access a properly formulated chicken feed. That is not your fault, you can only do the best you can with what you have available. If the chickens can provide for your needs, then it doesn't matter too much if their eggs are a bit smaller, feathers weaker, and lives a little shorter. They're still living better than any hen on a factory farm. But if/when a better feed becomes available on the market, I'd like to encourage you to try it out and see the difference after molt.