I am also looking into building a
fodder system for my 3 cows, numerous chickens, and 2 pigs. I have been doing a lot of research and planning for how I want to set it up. So keep in mind this is coming from my own research, not coming from a point of
experience.
I have determined that for large scale fodder systems (like for cows), instead of trays, look at using a roofing panel (like in this system here:
https://m.youtube.com/watch?v=dJVkhns1rhs)
All I have seen in regards to thrifty use of water is that reusing water often causes mold after one or two uses.
As for seed type, I plan to use barley and wheat due to availability and a lot of people say those are quite palatable.
Anyways, hope that helps!