IIRC from information provided by
@U_Stormcrow, oatmeal is too high fiber to be healthy for chickens in any but the smallest quantities (which would be miniscule for chicks).
A good quality chick starter feed already has the "healthy nutrients" they need. Pasty Butt is usually caused by some kind of stress (or a genetic propensity) -- often related to heat or shipping.
Oats are high in beta-glucans, which can contribute to sticky poops. I would NOT offer that to birds already suffering pasty butt. Barley as well. Then Rye. Barley and Rye are less likely to be "off the shelf" solutions for most chicken keepers, however.
Sticky poops are often associated with high stress conditions, shipping particularly, but also heat stress. I find (
**anecdotally**) that offering feed as a wet mash or even a started ferment (live plain yogurt cultures swirled in) can be beneficial in assisting to resolve some of those issues. I can NOT point to any studies supporting my observations, and it may relate to my hot humid climate, or some other factor I am unaware of.
/edit I am not the fan of ACV that many are, though I understand the science behind it, both in the use of the "mother" to provide beneficial bacteria and the adjustment of pH in the gutt to alter the biome and select for different bacteria there. Most people don't know the pH of their water, so they are slapping the veneer of science over a process they are merely guessing at in hopes of altering the pH of their birds insides to a target they don't know, and can't measure, by adding a difficult to measure amount of acid to a waterer of uncertain capacity. and then wating for the newly introduced bacteria (if they used the "mother") to reproduce to useful levels.
Swirl in a tsp of lactobacillus-laden live yogurt culture into a half cup of feed, then add water till its wet mash. Give it some time to jumpstart many of those processes, add some useful enzymes, and incidentally ups water intake for the poor birds. Its still guess work, yes, but its a rather more direct process.
