Any more recent thoughts of opinions on this?
I can give an 'opinion' on it based on recent experience...
Since there are scientific studies that don't back it up, it could be just
post hoc ergo propter hoc (correlation does not imply causation) but anyway here is my experience...
This year during the month of June I was getting quite frustrated as I was only getting 1 or 2 chicken eggs a day out of dozens of hens... My Guineas were laying like crazy the entire month so it wasn't a dietary deficiency... The chickens eggs for some reason just started to drop off during the end of May and by June they were just eating machines giving nothing back...
Also worth noting my October hatches from last year were laying a single thing yet, and my birds get their full 16 hours of light (supplemented) every day regardless of the seasonal light changes...
And if anyone cares for this tidbit, they reside in a partially heated coop (about 40°F) all winter with supplemental light as well so egg production is even pretty steady during the winter months, so it wasn't a molting thing...
As for feed my chickens always have dry balanced feed available to them, but they also get fresh vegetables, bread, fruits or other things every day as I have a hook-up for free day old stuff from a local grocery store...
So on to my experience, during the first week of July I was given several cases of past the sell date toasted tortilla (corn chips) about half of them were jalapeno flavored, some were just labeled 'hot' and the rest were plain... I crusted the chips up and soaked them in water overnight to make a corn mash, and that was the chickens treat for several days... Within a few days all the sudden my bantams started to lay, I was up to about 8 bantam eggs a day... Come the second week the regular sized birds started to lay, including the October hatches that were not laying a darn thing (they are my only olive eggers so it was obvious when they started to lay)... It's now the end of July and I'm getting about 2 dozen or more full sized eggs a day, the bantams all went broody (as did a few full sized hens) so their is obviously lost egg production from them, and probably others as they are now fighting over nesting boxes... I just installed four more nesting boxes today actually, because of the broody birds, so I expect production might climb a bit...
Now it might be a fluke, but I can say the next time egg production slows down I will certainly give spicy food another roll of the dice, it certainly didn't' hurt anything...