Here is a suggestion
You didn't say what the allergies are to- is it something in the enviornment or is it food allergies? We went through a run of steroids with Zoom the very spoiled Malinois. I started making her food just after putting her through a series of allergy tests that were sort of inconclusive. I ran across a web site of this man, William Cusick, who is a dog nutrition specialist and he let me know that Belgian Malinois do not do well with certain foods and also they don't digest high fiber foods well. I changed Zoom's diet as I was feeding her a beef-based homemade food and now she gets chicken, fish, zucchini, green beans, green peas, carrots, potatoes, flax seed and bulgar wheat. I give her a powdered supplement for her skin too. She is doing beautifully on it all!
I looked up Mr. Cusick's info on Great Danes here:
http://home.att.net/~wdcusick/GreatDane.html and you can read what he has to say- maybe you even want to buy his book or contact him for a personal recipe but here is what I suggest for you to try:
5 lbs Lean ground beef (or venison if you can get it!)
1 whole Butternut or 2 acorn squash (unpeeled but washed carefully), cut into chunks OR 3-4 russet potatos, scrubbed and cut into chunks
2 lbs carrots
1 lg bag frozen green beans
1 small cabbage, cut into chunks
3 cups Whole rolled oats
1 cup Rye (am not certain what form you can find to put in the mixture)
1 cup Flax Seed
3 cups beef broth or water
Break up the ground beef and start browning it then dump in all the other ingredients, cover and simmer until potatoes and squash are almost tender (they will cook more as it cools down.)
This is off the top of my head so when you actually try it, use your own sense of how it should be to figure quantities. I personally do not use rice in dog food- it is just fill. If you feel you need something more, try barley.
I hope your beautiful dogs can eat this mixture- I hope allergies don't get in the way. If this doesn't help let me know further information and I will try to help.