VernAK
WKR
It depends on the area and moose vs. predator populations, other food sources, etc.
A research paper was published in 2015 (link below) that I found pretty shocking. The study was called "Evaluation of Brown Bear Predation on Ungulate Calves in Southcentral Alaska Using Neck Mounted Cameras, GPS, and Stable Isotopes." The study area was the Nelchina basin.
In short, over a three year period this study found that brown bears kill on average about 1.25 moose and/or caribous calves per day in the month surrounding the typical calving season, or roughly an average of 34 calves each in that time period.
Consumption among the individual bears in the study varied as well with the low end being around 14 or 15 calves in the study period, and the high end being 46 or 47 if I remember correctly.
The study also found that it takes a brown bear about 60 minutes to consume a moose calf, 40 for a caribou calf and little evidence of the meal is left when they are done, which is why previous studies on the same topic grossly underestimated how many calves were getting munched.
Link to the Research Paper
I've watched some of that video and it's quite revealing. It's amazing how little time the bear spends hunting and how much time is spent resting.