If it's me then have stated that fresh green grass is best for cattle - not hay, not straw.
As for the straw-man argument
"Toxins are a problem?" - Yes they are IMO.
I have suggested the toxins MAY only be concentrated in the grain and not the stalks (if that is wrong then then I can correct this guess to actual reality) - But even if the toxins are not in the stalks it still doesn't mean it's a better food than fresh green grass.
I buy from a farmer that has green grass all year round.
Though I try to be a realist and accept that some places don't have much green grass at some times of the year.
If supplementing of hay did not occur at times of the year in these places, then there would be no dairy or beef meat produced in these places for much of the year (in fact they would not keep cattle at all as they couldn't feed them all year round).