The bottom line is there are far too many variables to begin to predict what's in this hay, all the way down to the  weather when cut and time of day.  Nitrate is a concern with stressed forage too but in your favor is the relatively small percentage of the diet.  Just soak it and be vigilant.  If you suspect a problem, just go to 100% cubes until you can get safe hay.

Eleanor in PA
www.drkellon.com
EC Co-owner
Feb 2001