I used your number of 1/15.
Another interesting anomaly with feeding baleage I have found is that a baleage bale feeds almost as many cows as a dry feed bale. I know that goes against conventional wisdom but that's been our experience over the years.
Our bales are roughly 1700 lbs. Without any supplements, it takes 35 lbs a day of our feed to maintain a cow to calving, more after. If we use the pie are round formula this would tell me we have roughly 1200 lbs dry matter in a silage bale. We calculate 35 cows to a silage bale and 48 to a hay bale without making the cows tell us we are underfeeding them.
In -40 and colder weather we have had our little cows clean up 45 lbs of hay.
The last years we have been supplementing with 5 to 8 lbs of screenings pellets. Finding the pulse crop screenings from one mill are worth paying a premium for as 5 lbs of them on warmer days will take the place of 8 lbs of hay at a similar cost per lb.