We have a field that was seeded down two years ago with winter wheat as a holding crop. It has self-seeded, and this year it has a fair amount of growth that has matured to the point of heading out but is still green. Can I graze my horses on this? There is other grass mixed in, so it's not solely wheat. If it is OK to graze them on it, should it be done for short periods (after the introduction period) or is it fine to leave them on it once they have acclimatized to it?
There should be no problem with grazing horses on green wheat plants, and horses really like them once they acquire a taste for them. The acclimation would be similar to any new turnout on pasture: gradual if horses have not been on grass for the winter but not necessary if they were on the field through the winter.
The one thing you might have to watch for is the beard on the wheat seed head. Some varieties are beardless, and if that is what you have, there are no concerns. If the wheat is bearded, then as the seed head matures (more mature than the stage it is in now), the beard becomes stiff and can be problematic for the horse, poking and possibly becoming embedded in the gums, causing soreness and abscesses. Many horses consume wheat beards with no problem, but there is a risk.
Other than the problem with wheat beards, as long as the horses don't overindulge, they should be fine on the wheat.