One of my mares recently had mild impaction colic. She also has had bouts of diarrhea and haybelly. At the vets request I had the barns hay tested and it was too low in protein (5.6) and lysine and too high in fiber. So now I need to get better quality hay which is very confusing so I would love to hear people's experience on the two types I am considering.

Orchard grass/ Alfalfa mix - approx 10-20% alfalfa
Orchard grass/Timothy mix - all organic and guaranteed

Diet instructions from vet is good quality hay with at least
10-15 % protein and good vit/min supplement. I have found the vit/min supps but I am so confused about the hay. Since the protein levels in orchard and timothy can very and test below 10%...I was thinking that the small amount of alfalfa mix might help keep the levels up. A 50/50 mix would be too high.

Both my horses are easy keepers and live in a pasture. The grass is minimal in appearance (less than qtr to half inch) but I am told that adds up so I will not be feeding much hay right now. And here in the NW we have had A LOT of rain which I believe can impact the nutrition of the pasture grass? When can I expect the nutrient value of the grass to diminish?

I have very little knowledge about hay and since it can cost about $230 a ton, I really don't want to make a mistake.