I have used Hubbard, but I was getting comments about my birds looking 'dry' from my mentors at the shows. Adding a little BOSS didn't work for the Cornish, they stopped laying, seriously no eggs at all. So I switched.
I have used Kent Multi-flock, but ran into an issue with some of my MGB Hens.
So now I am using Purina Flock Raiser. It has solved all the problems so far. Cornish seem to do really well on it they seem to keep good lean weight and look very glossy, and the MGB hens have straightened out. I am noticing that they are slower coming out of the molt, but I hadn't been giving kitten chow because I felt 20% was sufficient. Based on Chris' comment I will add some Mackrel and/or kitten chow and see how it goes.
I really wish I could go back to a pellet. The Cornish will not eat the fine crumbles or powder, but the Doms will so there's not a lot of waste there. I have had to change to a trough type feeder for some pens because they were wasting it from the hanging feeder. I noticed a lot more sparrows in the barn since the switch. I am putting up netting to hopefully keep them out this weekend.
I am seriously thinking of switching to the Kent 27% pellet and mixing in my own components to get to 18-20% protein feed, but havent had the time to price it out. Anybody have a good Breeder Diet based on the Kent 27%? I'd really like to see if it is doable price wise.