Perris, I am unsure why you persist in misreading me, and misunderstanding the research. I'm not the one who said
...But most of that research was done on birds that were not anatomically entire, and in particular had a significant portion of their digestive tract surgically removed (because it interferes with the results in ways the researchers couldn't explain, so they removed it, in typical scientific method fashion). That's the caeca, now recognized as a very important part of the biome. So not obviously a good paradigm for our entire birds. And we're only just starting to understand the biome.
Most would be more than half. I doubt you could find modern research with surgically altered birds comprising more than a few percent of the studies, if that. Certainly, I don't recall reading one published in the last thirty years or so, though of course there are plenty of studies which involve taking the bird apart at the conclusion of the experiment.
Lysine use's for relative measure is part of the "Ideal Protein" concept - which is important for commercial operations interested in reducing nitrogen waste by ensuring that the protein the birds are fed is comprised of the proper ratio of amino acids to support their biologicical process without excess or deficit. Lysine is then used as the reference, not because its unimportant, but because its relatively easy to measure its use, being involved in few biuological processes. Those processes, however, are mostly muscle creation and maintenance. Hardly unimportant.
I am not a proponent of the "Ideal Protein" concept, and you will not see me advocating it here - its focus is essentially irrelevant to the typical BYCer - though I'm familiar enough with the concept to work their ratios "backwards" to arrive at minimum recommended levels of particular amino acids. Historically, Ideal Protein began as a concept before we could even measure some of the Amino Acids directly (the Sulphur-containing Amino Acids particularly), and before the function of many amino acids was well understood. Nor is ideal protein concept unique to chickens - its also used for pigs, cows, sheep, fish, and other livestock. Its an evolving field, and one which can't offer a one size fits all solution to every breed at every age - but its not inherently bad science, its just focused on providing an answer to a question BYCers needn't trouble themselves with. Still useful studies for us, but only indirectly, as an analogue.
Neither am I the one who made this claim,
The nutrient figures for broilers are based on experiments done on birds up to 3 weeks (yes, 3 weeks) old; body maintenance beyond that is not an issue in those calculations because the bird will be harvested at 5-6 weeks old for KFC or suchlike and all they're interested in for the 'finishing' stage is weight gain.
The sources I linked, a mere fraction of what I read, largely (though not exclusively) suggest different feed regimens for different ages of broilers, not merely "up to three weeks". I keep the older NRC guidelines around in part to show how the state of the science has evolved over the years as compared with more modern study - and that feeds, largely, have not kept up.
Now this part:
A better descriptor would be 'conforms to the minimum nutrients required to keep the bird alive at least cost'. I don't know what age they test it to for all flock type feeds. They lose interest after 18 months for layers as that's when commercial producers throw their layers away.
Is largely true of layer formulations, and has been the source of one or two screeds by yours truly. (See,
for example). But that things are not well studied beyond those points is not reason to suggest "we can't know, therefore we should not make educated supposition." We know the negative impacts of reducing Met in the diet, reducing Lys, Tryp, Threonine, and a host of others. We know the buildup of calcium and its effects as a progressive pathology. We understand the importance of various vitamins. and on that basis, suggest continuing to provide levels of protein (as analog to amino acid contents) or minimum levels of certain aminos specifically which have been shown to have benefit in birds.
I'm not one of the layer advocates - the numbers I routinely recommend, based on what I've read, well exceed the typical layer formulation's levels of certain keys, while drastically reducing total calcium (as a part of the feed itself), allowing birds to self regulate calcium intake through seperate source - something studies suggest they do effectively. I also recommend higher than layer minimum levels of non phytate phosphorus, for its role in buffering the effects of excess calcium in the theory that it should result, on average, in healthier, longer lived birds.
and that's as much time as I intend to spend knocking down your strawmen.
As I've said before, Its Complicated. But the studies (in general) are not so flawed and uinreliable as you seem to suggest - nor is there any ready, more reliable, alternative.
