Medicago sativa was cut with John Deere 920 MoCo mower/conditioner during first harvest of 2005 at the University of Wisconsin Arlington Research Station.  The mower has a 3 m cutting width and forage was cut with deflectors moved to result in either a wide swath (72 % of cut area) or a narrow windrow (25 % of cut area).  The forage was 170 g/kg^-1 dry matter when cut.  The two windrow types were produced as split plots in two production fields.  Forage was harvested when at 350 g/kg^-1 dry matter and put into silage tubes.  Fermented silage was sampled six weeks after harvest and analyzed for forage quality and fermentation products.  Forage, in wide swaths, reached 350 g/kg^-1 dry matter in about 10 hours and could be harvested for haylage the same day as cutting.  The same forage put into a narrow windrow was not ready to be harvested until later the next day. Alfalfa from the wide swaths had 23 g/kg^-1 less NDF, and 18 g/kg^-1 more NFC.  The NFC difference is both a quality loss (due to loss of sugars and starch) and yield loss as the 18 g/kg^-1 loss in narrow windrows was to respiration.  Haylage from the wide swath had almost 10 g/kg more total digestible nutrients and 10 g/kg^-1 more lactic and 5 g/kg^-1 acetic acid.  It also has 15 points higher Relative Forage Quality.  Ash content of haylage from wide swath alfalfa was less than from narrow windrows even though the wide swath had been driven over and the narrow not.