I am not 100% convinced that feeding higher protein feed to meat birds makes any difference in growth. I've raised birds on 18% chick starter and the last batch on 20% grower. There was no detectable or significant difference in the grow time for these birds. Does anyone have research showing that high protein feed produces faster growing birds?
I find your percentages interesting. Here Starter for chicken chicks is 20 to 22% and Grower is 16%. I'm not sure what you are feeding yours? Here is a link to a Florida extension site about feeding broilers. It might be helpful. Feeding Broilers http://edis.ifas.ufl.edu/ps035
If you used two different batches of birds there may have been enough of a difference between breeding that the protien difference wasn't noticable. If you really want to compare get a batch of chicks and divide them in half and feed each the same amount of feed for the same amount of time. Then you will have the same genetics on both types of feed to compare.
