The 10% recommendation has never yet been backed up on BYC with any sort of proper reference to explain why anybody believes this; it is, in other words, just hearsay: people hear it and repeat it without question - so citing a thread or blog or other unrefereed source where it was said without support is just repeating it again.
The word treat means whatever the user wants it to mean on BYC. It is used by most posters who respond to such questions to describe anything other than commercial ultra processed feed - to describe real foods in other words. Thus it is doublespeak, the ultimate distortion of the truth by meaning the opposite of what it actually is. Real food is not a treat. Real food is essential for nourishment and health.
"Thus it is doublespeak, the ultimate distortion of the truth by meaning the opposite of what it actually is."
A little inflammatory, doncha think. Well, I found it so, anyway.
"never yet been backed up on BYC with any sort of proper reference to explain why anybody believes this"
Here you go:
Link
if the link doesn't bring it up:
Kidd, M.T., Maynard, C.W. & Mullenix, G.J. Progress of amino acid nutrition for diet protein reduction in poultry.
J Animal Sci Biotechnol 12, 45 (2021).
https://doi.org/10.1186/s40104-021-00568-0
Imho, you can even use this source, and some of its references in your crusade against ultra processed "food" to very good effect.
I don't like that it is the tired old example of protein or that it is about broilers but I have other things to do today than find the same concepts in the research regarding fats, minerals, and so on. And for chicks, layers, breeders. All that has been done and published. Extensively.
Short version:
"...The present review was written to provide insights on further reducing dietary protein in broilers.,, nutritional research areas of low protein diets, [and specific amino acids] have been assessed and combined in this text, thus providing concepts into reduced protein diets for broilers. In addition, linkages between the cited work and least cost formation ingredient and nutrient matrix considerations are provided. ...
Investigations in reducing dietary crude protein (CP) in chickens began in the early 1940’s, which commenced nearly a century of exploration in this area of poultry nutrition research. ...Lowering CP more than 30 g/kg has been shown to inhibit performance and increase adipose fat deposition...
Utilization of the ideal protein concept allows for precision feeding of poultry.... However, additional amino acids must be continuously assessed as their minimums can vary based on dietary protein status, bird strain, bird environment, and company production objectives to satisfy economics....
Diets with decreased CP and increased starch flood the small intestine with glucose and compete with amino acids for absorption through their respective sodium dependent pathways..."
The above combined with a few assumptions:
- protein is the most expensive part of the feed hence the usual goal is minimal protein
- adding anything that has lower protein than the rest of the diet otherwise would will lower the protein of the diet*
Results in a logical conclusion:
If the main diet of the chickens is a commercial feed then adding grass and veggies scraps (or anything else low in protein) will lower the protein of the diet as a whole.
So, why is 10% okay?
It may not be for any given bird. It may not be for any of the birds in a given flock. I think it isn't without at least some consideration to what the treats are and the differences (if any) between the needs of this bird or flock and the needs of the birds typically used in research.
But the vast majority of those asking want to feed handfuls of whatever it is, or the bowls of scraps of vegetables from fixing their own dinners, to two, three, six, maybe a dozen or so birds. Few realize how big a percentage of the chicken's/flock's diet that is. Giving an amount that is okay leaves the door open for learning about chicken nutrition.
Ten percent has a chance of actually being okay because, as the above source puts nicely enough, "...[amino acid] minimums can vary based on dietary protein status, bird strain, bird environment..."* and, I'd add, other things. So, they have to add some margin. I doubt it is ten percent but combined with the chance that a given flock needs the lower end of the range and with the chance the treats might be varied gives at least a theoretical hope for it.
*If you follow the references to the references to get to the peer reviewed study on how much the minimums can vary, you will get to a chart that gives requirements for individual amino acids ranging from 5% difference to 30% difference (MET being 25% difference, Lysine 25%). That one measured bird strain and male/female differences in 21- to 28-day old chicks. See, not heard and repeated without question. That is, of course, probably not among the studies I looked at over the past several decades but it gives similar numbers. Nothing so easy as each one being exactly and only ten percent different but enough to conclude 10% is a reasonable variation while still giving a reasonable amount of margin.
Ten percent is easy to remember, sort of easy to measure, big enough that most people feel like they have given a treat (defined here as something out of the ordinary that gives pleasure), small enough to not cause too much damage even if it isn't actually okay.
I respectfully suggest you try to make your case without indicating other people are unthinkingly giving double-speak.
Edit for spelling