TxJim has this absolutely correct. Much research has been done on this the last few years. Wide swath vs narrow. When hay is placed into a narrow windrow, not only does it take longer to dry, but the plant actually continues to "respire" (live), burning up valuable carbohydrates, effectively lowering the nutritonal value.
Dr. Tom Kilcer was the pioneer with this research. He is (was?....not sure now) with Cornell University and he did exhaustive research into this. Look him up on the internet. VERY eye opening and informative. His work was so conclusive that many companys started adapting their equipment per his suggestions. I have personally spoken with him at length in the past regarding his work. Fine man.