Congratulations on your broody.
I don't have much of a heat stroke concern here in western WA, but when I lived near Atlanta GA I had to do some inventive things to keep Sydney comfortable (my pet broiler chicken with heart disease). I've had good luck cooling a coop by mounting a medium to large fan (or multiple fans) at the highest possible window or vent and blowing the rising hot air out, and at the same time have a small to medium fan at floor level blowing cooler (ground level) air in. I had a large chest freezer, and I would fill up numerous 2-liter soda bottles and gallon milk jugs with water, and keep them in the freezer. On days that were really hot I would put one or more of the frozen bottles in front of or behind the fan so that the air that was pulled into the coop had passed over ice first -- instant air conditioning!! The gallon jugs have a lower surface to volume ratio, so they don't cool quite as well or as quickly as the 2L bottles, but they last longer, so you can adjust how cool you make it and how long it lasts by how many jugs vs 2L bottles you use. Once they're melted, you just put them back in the freezer to reuse. They do produce a lot of condensation on the outside of the bottle as the ice inside melts, so I always set mine in a pie tin to keep water from getting all over the floor. Any pan or dish with very low sides would work well for that purpose. Another important point is to remember that water expands when it freezes, do don't fill the bottles all the way to the top (probably 1-2 inches of headspace is adequate), and don't put the caps on all the way when they're put in the freezer, or they will burst open and leak water all over in the freezer. On days when it was 100 degrees and 95% humidity, this sort of cooling was lifesaving.
Shadecloth (available at most large nurseries, greenhouse supply businesses, big box stores with a nursery dept, and online) can be invaluable. It isn't super cheap, but it can really bring the temperature down in outbuildings. It should be suspended at least 2 feet above the coop, and extend out far enough on all sides that sun doesn't hit the coop directly at any time of day, although the wider an area of shade that is provided around the coop the cooler the ground will stay, and therefore the cooler the coop will stay. It can be suspended with relatively little expense using vertical, 2"wide PVC pipes with a "T" connector at the top, then 18-24 inches of horizontal pipe connected on each direction of the "T" to distribute the stress on the fabric, and the horizontal pieces can be attached to the shadecloth with cable ties (zip ties) if needed (I usually only do that along the edges, but not in the central areas unless wind is a problem). Shade cloth comes in different grades for different amount of sun blocking, so try to get the best quality you can afford. If you contact a farm that uses greenhouses for commercial purposes, many of them will use shadecloth seasonally to keep the greenhouse from getting too hot. You might be able to get on a waiting list for their old shadecloth when they replace it (eventually it tears in places). I found a huge piece (about 100 X 200 feet) of very high grade shadecloth in excellent condition at my local Habitat for Humanity store (a local second hand store for building materials -- I love that place) for only $50 last year. I snapped that up immediately. They also make "instant pop up" canopies of various sizes that do the same function. You can get small ones for $75 - $200 at most stores that sell outdoor or camping supplies, but those might not be big enough to adequately shelter your coop. Here's a link to the FarmTek company, after I typed "shade" into the product search slot on their web site:
http://www.farmtek.com/farm/supplie...0&ftSearchDefaultPerPage=50&searchQuery=shade. I don't typically buy products from them unless they're on supersale, as their products are excellent quality but too expensive for my farm budget. But I use their website to collect lots of problem-solving ideas. Lots of the products that they have I can make myself at less cost, but are things that I would never have thought of had I not seen them first on their web site.
On especially hot days, when even the shadecloth plus the fans plus the frozen jugs were inadequate, I would turn on the sprinkler. I had a sprinkler that sprayed in a tall arch and alternated water back and forth across the lawn. When I ran it on really hot sunny days it created a local temperature differential, which created this wonderful cooling breeze through the entire yard. I typically ran the sprinkler for 30 minutes, and the cooling effect lasted 1-2 hours longer. It's not a very efficient way to water a lawn, and not legal in many areas during a drought, as most of the water evaporates instantly, but it is very cooling when there is no other option. And for Sydney, because of her health concerns, I always had the option to bring her into the air conditioned house. She had a permanent pen set up in the guest bedroom, just in case. With my current broody, she is brooding in a permanent hospital run set up in my computer room because the broody pen is unavailable until next week. She's doing great. That might be an option for you if you've got the extra space, although you'd have to figure out what to do when the chicks hatched. But you could start her brooding inside, just to give you enough time to get your coop remodeled for better cooling, then move her to the modified coop before the eggs hatch.
You may already have this information, but here is the contact information for the district director of American Brahma Club in your area. She may be able to help you find some fertile Brahma eggs in time.
District 5 / Nebraska, Kansas, Oklahoma, New Mexico, Texas, Louisiana, Missouri, Iowa, Arkansas
Dee Mejstrik
22443 Devore Avenue
Glenwood, IA. 51534
(402)917-1907
[email protected]