According to both those sites, my horses should all be foundered beyond use, my old horse that had cushings, got the pregolide , lived on oat and alfalfa hay, should have been diabitic, foundered etc..
Yeah, different horses & situations/climates grass is grown on, etc, etc have a bearing, so there are only generalisations, not hard & fast rules. Tho your horse having Cushings is one thing that points to their situation/diet not being so rosy.
One article says don't feed grass hay, to much sugar. All the studies refer to cool nights ,freezes, etc.. I don't think alot of this applies to the area I am in.
Yes, grass/hay, depending on type, how it's grown, cut, the climate, etc, can indeed be high sugar/starch. Generally the 'improved' varieties, grown for cattle fattening & seed production are higher starch & native grasses are lower. Sugars increase in grass with photosynthesis and decrease through growing over night... unless grass is stressed due to frost, drought, overgrazing etc, when it retains the sugars over night. Sugars are only 'lost' when grass is growing & retained after cutting/drying. So stored hay will likely be just as rich as the grass it came from & if cut on sunny afternoon, sugars will be higher. It's all a bit complicated the more you look into it... You can also leach sugars out of hay by soaking before feeding, if it's too high sugar.
There are definitely studies that have been done on different grass/hay NSC levels, that show cereal grasses to be very high, but I can't remember where I last saw the info. In the meantime, take a look at a link Desert just posted on another thread... Diet for the Insulin Resistant Horse | Equine MedicalEquine Medical