I went to that website and got bored and came back. What a long explanation of mixing. Sorry, I didn't get through it.
I give my Muscovies a bowl of Feed and a Bowl of Scratch grains and let them decide what to eat. Every other day I sprinkle Nutritional Yeast on the Scratch. Some days they just forage and don't touch either. Chickens clean love cleaning out thier dishes in the morning though.
I have noticed this week they are eating the feed and grains more and really putting on the weight. Big Time. Getting ready for winter. Bigger than last year. We may be in for it this year and we are in the South.