I may have missed it but I didn't see anything that stated how you keep your chickens.
The layer v other feeds is exactly as ChickenCanoe writes. It's one of those it does what it says on the tin answers.
There is an added complication I've found with free rangers who get mealtime commercial feed. Roosters that have hens tend to spend most of the groups forage time keeping watch for predators while the hens eat. When he does dig and find something good he calls his hens, or even picks it up and drops it in front of them. So, ime roosters get less to eat during the daily forage hours and eat more of the commercial feed than the hens at meal times.
The kidney damage is cumulative but ingesting high levels of calcium in a shorter period of time exacerbats the problem.
The layer v other feeds is exactly as ChickenCanoe writes. It's one of those it does what it says on the tin answers.
There is an added complication I've found with free rangers who get mealtime commercial feed. Roosters that have hens tend to spend most of the groups forage time keeping watch for predators while the hens eat. When he does dig and find something good he calls his hens, or even picks it up and drops it in front of them. So, ime roosters get less to eat during the daily forage hours and eat more of the commercial feed than the hens at meal times.
The kidney damage is cumulative but ingesting high levels of calcium in a shorter period of time exacerbats the problem.