Because chickens grind their food within the gizzard instead of with teeth, they in their diet.

They require Sand and  gravel

grit

"Because chickens have gizzards for grinding their food instead of teeth and the gizzards require grit, chickens need grit in their food." from my online class :)

i think that is new experiments yield untrustworthy data and should be carefully considered, because you don't know what will happen with the experiments.