Intensive Cutting Management of Alfalfa-Based Mixtures.

Cutting forages at an early stage of development allows for the production of high-quality forages but at the expense of yield and persistence. Our objective was to quantify the effect of cutting management on the forage yield and nutritive value of alfalfa-based mixtures at four sites from climatically-contrasted regions of Canada (1360 to 2260 Growing Degree-Days). The experimental treatments include four alfalfa-based mixtures (pure alfalfa; alfalfa + timothy; alfalfa + tall fescue; alfalfa + timothy + meadow fescue) and four cutting regimes with different intensity levels (cuts at early bud with a fall cut; cuts at early bud without a fall cut; cuts at early bloom with a fall cut; cuts at early bloom without a fall cut). Cutting management significantly affected annual forage dry matter (DM) yield and in vitro true DM digestibility of all four alfalfa-based mixtures in the first two post-seeding years at the four sites. Averaged across the four sites, a fall cut increased annual DM yield in the first post-seeding year but it reduced annual DM yield the following year. The greatest annual DM yields were obtained with cuts taken at the early bloom stage rather than at the early bud stage of development even though one less cut was taken. The forage in vitro true DM digestibility was greater when cuts were taken at the early bud stage rather than at the early bloom stage of development in both years. The intensive cutting management of the four alfalfa-based mixtures with cuts at the early bud stage of development and a fall cut reduced the estimated milk production per hectare. The production of more digestible forages with intensive cutting management does not seem to compensate for the yield loss.