Hi Patrick, thanks for the input.
You are right that 6 days cumulative grazing (3 days lead with sheep and cows plus 3 days follow with broilers) will cause overgrazing during the warm growing season. I should have clarified on that point..
We are planning on starting the broilers in April on the neighbor's degraded pasture where the flerd will be grazing paddocks carpeted with hay rolls. I am hoping the chickens will scratch and manure into the remaining hay mulch and help promote good spring growth while still leaving some decent ground cover. I will also do some diverse cover seeding before laying down the hay.
This should keep everyone busy into mid-June, at which time our better established pasture will be quite high and the first batch of broilers will be in the freezer or hopefully sold. Usually June through July I will make more frequent moves of 1-2 days with the flerd. I will just have to see how much time it takes and how sustainable it is of a work flow with broilers. If the broilers are causing too much disturbance, we will skip them during the main warm season and maybe do a second round in September. But the early spring batch should really help jumpstart the "new to us" tired pasture and beat the broomsedge and other weeds.
I think the real pasture management advantage of broilers is high disturbance targeted usage. If I can turn many tons of organic feed into a powerful, balanced soil amendment and distribute it with a bucket and a 4wheeler instead of a tractor, that is a big win for me.. not to mention raising a thousand broiler chickens as a result! All considered, that is a tremendous amount of input and disturbance, so it needs to be used mindfully.
This is my main point of contention with Salatin and the "salad bar" grazing model and his original Pastured Poultry Profits book.. I suspect that it burns up OM and ruins the soil if used regularly, multiple times throughout the growing season every year in perpetuity. This seems obvious if you look at the aerial photos of his farm.
Anyway, thanks for the encouragement and comments. I will update this thread as things take shape.