I'd offer it free choice every now and again this winter in a separate container. That way, if they need it, they get it, if they don't, they won't partake.
If you notice them partaking too often and ignoring the feed, only put it out as a weekly amount. Make Saturday, or whatever day, bone and blood meal day.
As with any nutritional supplement, if it taste too good to them they won't stop until that is gone and they will ignore their regular nutrition, which is not ideal. High pro feeds are meant as a supplement to a more normal supply of protein.
Same with giving "treats" like BOSS and wild bird feeds...high pro mixes that, if given daily, gives them more protein than they can utilize in a healthy manner. Birds need it because they fly and have to move constantly to gain their daily food...chickens do not.