Our Web site searching found that oats, at milk stage, contain a mliky substance in seeds. To confirm that, here's what we found from the University of Florida extension on harvesting small grains for silage, taken from its Web site at http://edis.ifas.ufl.edu/DS155:

"There are typically three stages of identifiable plant maturities at which small grains are harvested - boot, milk, and dough stages. The boot stage is the time when the head is enclosed by the sheath of the uppermost leaf. The milk stage is when the grain head releases a white liquidy substance when opened. The grain head continues to lay down carbohydrates so that its consistency becomes more dough-like thus the label 'dough stage'."