Commercial feed is designed for commercial farming operations in general. It will provide a good basic nutrition. We have often discussed on this thread how chickens, when given options, will change what they eat based upon what they see their needs as being.
Molting being the biggest example. In most cases, chickens who are molting are looking for higher protein feed and may sun commercial layer feed for other foods sources.
The 90/10 rule really applies if you are their only source of feed. If your chickens can scratch for worms and bugs, eat grass, etc. then you are actually only providing a small amount of their nutrition via chicken feed. There is no realistic way to judge a 90/10 ratio as they may spend the whole day eating nothing but seeds.
I give my chickens a lot of credit for knowing what they need to eat. There is feed available at all times. They eat very little feed outside of the winter. They seem to know not to over graze any one food source in the yard. In fact, they will leave corn and meal worms for later if I do give them some.
In short, I have learned to provide options and trust them to eat what they need. I think it has worked for me on the most part. I do think Aurora is a little over weight but that is her choice. I can't really stop her from eating. And now that she is queen, she has dibs on everything.
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