OK, Davie FL is down by Pembroke Pines and Sunrise - I don't know any local mills in the area. Yes, you are wet, and hot, pretty much all the time. I think that's USDA growing zone 10, almost 11? That takes a lot of traditionally "winter" crops, and numerous good grasses completely out of the realm of possibility.
AND apoologies for saying straw earlier, I meant hay, but neither is great nutrition - straw obviously much less - just depends on what the hay was made from and when it was harvested.
Spent brewers grains are an excellent cource of proteins and useful enzymes for making other grains more bioavailable. Moderately high fiber, and only a bit high in fats. Relatively low energy, of course, as the carbs have largely been extracted and converted as part of the brewing process.
Exact nutrition depend upon which grains were used in making the wort, at what temperatures, and with which adjuncts. An all 6-row malt for an imperial stout has a different character than a 2-row and rice malt for a helles munich. The spent grains are usually sold wet, which will mold pretty fast (NOT good eats!) if you don't have a way to dry them.
For myself, I stretch my feed with
a biodiverse polyculture - which is to say I've deliberately planted my grounds with a host of plant life, not in cultivated stands, with the goal of ensuring I have options available to my birds to range on throughout most of the year. I'm trying to ensure they have at least one grass, one small grain, and one legume available most of the time. I have a number of grasses planted (scribner's panic grass does well for me, but also orchard grass, st aug, fescues, perennial ryes), am struggling to establish various grains and near grains such as sorghum, amaranth, millet, teff, sorrel, sudangrass, flaxes (harder now that the birds gobble up the seed almost as rapidly as it establishes), and a number of legumes (including four varietes of clover now and a small amount of alfalfa), plus a large number of herbs and forbs. To keep fats down, I have deliberately not planted some of the concentrated fat seed sources, like sunflower. During peak season, it bends my feed bill 30-35% - we started that a couple weeks back, and rain permitting, it will continue this way till late fall.
AT 50# a day, your flock sounds to be about 3x the size of mine - I'd guess you are somewhere near 200 birds? But dealing with roughly the same amount of land - my cleared pasture is just under 2A, thought they also range the surrounding woodline. Your soil quality will determine whether the grounds can support that load or not - my grounds will support an flock much larger, so my plantings continue to colonive my clay soils and self propogate - if you have very poor soils down there (and much of the area is), you may need more intensive farming methods than I use.
In any case, I reccomend checking out what you can get as cast offs/by products from other facilities - particularly your local brewer. When you plant, within the limits of your soils and climate, I'd recommend trying for plants that are high value and not produced at commercial scale - you will never compete with a midwestern corn (which is borderline anyways) farmer, and you aren't well suited for wheat production, but may do well with some of the smaller grains as I am trying to do.
Teff, Sorghum (if its not too wet), and Sorghum/Sudangrass hybrids should do well for you. I really struggle with Crimson clover - we get a bit cold at times, but it should perform better for you. Some of the other clovers will do well. I can't provide specific recommendations in the pulses, none do well for me. Oh, I've been pretty pleased with fenugreek as well - the seeds are one of the better plant methionine sources, and the plant itself - much like oregano - tolerates mediterannean climates well.
Check with your local extension office - they should have good ideas as to what is being used as cover crops locally, and sourcing - then select from those with an eye to ensuring they have different periods in which they come into their prime in order to extend your "harvest".