It does help, I also give them boss before bed time. I normally toss about a cup on the floor of the coop for 25 hens. Gives them that little bit of extra protein to keep them warm at night.
Just be certain to have grit free choice in their coop in the winter if their run is snow covered. They will need that to break down the boss. I'm sure you know this though if you are already feeding them oats.
Boss? What's that? Snow???? What's that? My poor hens live in semi desert. 110 day, 65 night in summer, but winter does get and stay cold by our standards with open air ventilated coops. I don't have grit, but our soil here is DG. Decomposed granite. Little pebbily rocks and granules. Hope that's enough.