Best source of recommendations/reference for optimum nutrients in chicken feed?

Unfortunately a lot of the research done on chickens is for commercial birds as that's what's profitable. There isn't much money in backyard poultry research unfortunately so you're not really going to find much that isn't for commercial poultry
That’s what I was guessing, although I see frequent comments such as ā€œcould use more methionineā€ or ā€œnot enough lysine.ā€ I’m curious what’s being used to evaluate things. Thanks!
 
Unfortunately a lot of the research done on chickens is for commercial birds as that's what's profitable. There isn't much money in backyard poultry research unfortunately so you're not really going to find much that isn't for commercial poultry
This is an acknowledged limit of the research, yes. Easy to find research on broilers to about 8 weeks. Easy to find research on production layers for their first year of lay. Other than that? Educated guesses and reasonable assumptions is all we can do
 
I don't know if USDA and various county extension service recommendations are for optimum nutrients or for minimum that large-scale factory ag can get away with. I want healthy backyard hens, not barely-alive egg-popping ones.
Alive and laying eggs is a good start. Feeds that do not keep the chickens alive, or have them alive but not able to lay eggs, are not what you want either.

Laying eggs is a reasonable indicator of good health in laying hens. Missing nutrients will cause the rate of egg laying to go down. Hatchability of eggs will tell you a little more, because sometimes a hen can lay eggs but they don't have all the right nutrients to produce a healthy chick.

If you track down the research on individual nutrients, you can sometimes find how they set the recommended levels. For some nutrients, like salt or calcium, too little or too much can make the birds less healthy and less productive. There is an in-between amount that seems healthiest. For some other nutrients, there is a sliding scale where one amount is not enough, more is better, even more is better yet, and higher-yet levels are expensive enough that it's not worth the money commercially. Sometimes there is level that is so high it causes problems, other times you will never really get a high enough amount to cause problems.

I'm generalizing because I haven't studied it enough to know about most of the individual nutrients, just the basic ideas.

I'm not trying to say that the research gives the optimal level for chickens to live a long healthy life, but people who care about profit will care somewhat about the health of the chickens, because dead or unhealthy animals do not produce well enough to be profitable. So up to a certain point, their goals do overlap with yours. That makes their research one amount useful even for backyard flocks. The trick is to know where their information is correct for your purposes, and where it is not, and that gets complicated!

I'm glad to see that U_Stormcrow is going to post about it when he has time. He has studied much more than I have about the details of chicken nutrition.
 
...I don't know if USDA and various county extension service recommendations are for optimum nutrients or for minimum that large-scale factory ag can get away with.
Link below talks about this. The short version is that it depends on which edition you use because the goals changed. Also, having a goal and meeting that goal are different.

It depends on your definition of reasonable.

If you are looking for values you can use to build feed calculators so you can plug in ingredients and get optimal levels of everything (or, maybe of anything) or at least not have to worry about missing the windows between deficient and toxic - no, it isn't a reasonable source.

If you are looking for the best available source - yes, it is a reasonable starting place.

You might find this helpful: History and discussion about the Nutrient Requirements of Poultry

It touches on many of the reasons the Nutrient Requirements of Poultry is the best available and yet isn't what you seem to be asking for.
 
Alive and laying eggs is a good start. Feeds that do not keep the chickens alive, or have them alive but not able to lay eggs, are not what you want either.

Laying eggs is a reasonable indicator of good health in laying hens. Missing nutrients will cause the rate of egg laying to go down. Hatchability of eggs will tell you a little more, because sometimes a hen can lay eggs but they don't have all the right nutrients to produce a healthy chick.

If you track down the research on individual nutrients, you can sometimes find how they set the recommended levels. For some nutrients, like salt or calcium, too little or too much can make the birds less healthy and less productive. There is an in-between amount that seems healthiest. For some other nutrients, there is a sliding scale where one amount is not enough, more is better, even more is better yet, and higher-yet levels are expensive enough that it's not worth the money commercially. Sometimes there is level that is so high it causes problems, other times you will never really get a high enough amount to cause problems.

I'm generalizing because I haven't studied it enough to know about most of the individual nutrients, just the basic ideas.

I'm not trying to say that the research gives the optimal level for chickens to live a long healthy life, but people who care about profit will care somewhat about the health of the chickens, because dead or unhealthy animals do not produce well enough to be profitable. So up to a certain point, their goals do overlap with yours. That makes their research one amount useful even for backyard flocks. The trick is to know where their information is correct for your purposes, and where it is not, and that gets complicated!

I'm glad to see that U_Stormcrow is going to post about it when he has time. He has studied much more than I have about the details of chicken nutrition.
Thanks! At 70, I’ve gone back to college to get my BSc in ecology. This whole ā€œsort of this, depending on whatever that is doing, unless such-and-such factor happensā€ is very familiar, as we learn of the subtle complexities and interrelationships of life on this planet.
 
…If you are looking for values you can use to build feed calculators so you can plug in ingredients and get optimal levels of everything (or, maybe of anything) or at least not have to worry about missing the windows between deficient and toxic - no, it isn't a reasonable source.

If you are looking for the best available source - yes, it is a reasonable starting place…
lol, thanks. Best we can hope for, I guess. I used Merck’s human medicine reference in my pre-retirement years, so I’m familiar with its layout and approach.

Oh, this is really nice! I really appreciate your posting it.
 

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