Siouxbee,
I am not sure where you live, but in the NE here, fall is the best time to reseed a lawn (or very early spring), because of crabgrass. It only germinates in warm (no frost) weather, so if you try to reseed a lawn up here in warm weather, you'll end up with mostly crabgrass, especially by the second year. Here in southern Maine, the BEST time to reseed a lawn is in the first half of October. The grass has enough warm days to establish -it doesn't mind a little frost- without competition from crabgrass.
In any case, does your yard have any part of it that's not grass where the chickens could still roam, like around the perimeter? Last summer I used a cheap roll of wire fencing that I just propped up in various places to kep the girls off a particular area (or made a circular "corral" where I WANTED them to be). They totally respected the fence even though it was only 3 feet tall and could be knocked over by a gust of wind!!
One thought I had is that you could use such fencing to close off half your lawn this early spring, and reseed it, get it growing all summer.... and then in fall, fence off the other half and reseed, and it'll be good by next spring.
One last thing: we had really good luck (doing a whole huge lawn reseeding) with the products from gardensalive.com. All of their lawn fertilizers and stuff are , if not organic, at least free of toxic chemical perticides and herbicides. Now that we have chickens I won't use any traditional petrochemical fertilzers or treated seeds in our lawn because the girls eat the grass and we eat the eggs!
Hope this helps,
Stacey
