We have mangalitsas. Foraging on ample natural foliage + eating fermented grains, our sows were just 150lb~ going into their first winter at 9 months old. At 2 years old now they're maybe 450lbs. They love foraging and will happily feed themselves if at all possible. However, they're a notoriously slow growing breed.
For example, their piglets this summer, who were half hampshire, were 200-250lbs at 4-5 months old. The hampshire boar who fathered them exploded from 600lbs to 1,000lbs in 4 months, at which point we had to butcher him at just 2.5 years old. I would anticipate our mangalitsas taking 3-4 years to reach 1,000lbs.
I don't think you can grow a mangalitsa to 200lbs in their first season now matter how much food you offer. We weren't "trying" to grow our sows since they are our breeders, but they still had virtually free-choice feed, and they did grow faster than manglitsas are "supposed" to grow, reportedly averaging just 150lbs~ at a year old.
They do love to eat
hay, even grass hay. That's what we supplement alongside grain and forage. So I couldn't say anything from experience about alfalfa.