As I mentioned, we typically get 4 or 5 cuttings a year.  Also, I consider 4-5 years to be an old stand, and time to replace.  I recall reading an article once - most likely in Hay and Forage Grower magazine(?) - about a guy growing alfalfa in Montana, as I recall. He was getting 1 cuttings a year, and sometimes a second cutting. I believe he was getting stands lasting 10 years or more.  I came up with my conclusion: alfalfa will last about 20 cuttings in their lifetime. The more cuttings you take in a year, the less years a stand will stand. Right or wrong, those conclusions see logical to me.  Just a thought I would toss out there.