I have free range chickens and some in pens. I feed flock raiser all the time and supplement with oyster shell. I also feed a variety of other foods. I have found that sometimes switching feed/brands suddenly has made a few of my birds sick. Also, when young roos start to mature, they turn into hormone crazed monsters for a few months and really stress the hens. A young hormone crazed roo with just a couple of hens can cause an enormous amount of stress on the ladies. If u do by chance have more than one roo, they will stress%mate ur hen to the point of killing her. I have 16 free range hens that run with a RIR, i let one of the orpington cockeral chicks stay, as i thought 2 roos could manage fine w/ 16 ladies. That orp roo stressed my hens so bad, one got sick and they quit going n2 the coop to avoid him, and egg production went down. Some roos r just hard on hens! He had to go. Chickens produce cecal poo several times a day, its very stinky, and can look like diarrhea. Cecal poo is normal, comes in all shades of brown and can be mistaken for diarrhea. While chickens are growing, they still need something more than layer feed. It does not have enough protein.