Yield, persistence, and nutritive value of autumn-harvested tall fescue

Tall fescue, harvested or grazed in autumn, may be a potential source of forage but little is known of the effect of a fall harvest or grazing on yield and nutritive value of tall fescue in the mid-north of eastern Canada (approximate to 1400 growing degree-days). Three tall fescue cultivars (Courtenay, Kokanee, and Montebello) were submitted to 10 harvest management treatments (two dates of second harvest and five dates of third harvest) over 3 production years in the Saguenay-Lac-St-Jean region (QC). The cultivars Courtenay and Kokanee were more productive and persistent than Montebello. The annual DM yield decreased by an average of 15% between the first and the second production year and by an average of 35% between the first and the third production year; these decreases were greater (22 and 41%, respectively) when the third harvest was taken in early October. Increasing from 28 to 35 d the interval between the first and second harvests increased DM yield of the second harvest by more than 0.5 Mg ha(-1), but caused a greater reduction in DM yield of the third harvest, primarily during the first 2 production years. Third-harvest DM yields of more than 4.0 Mg ha(-1) were obtained in the first and second production years, while third-harvest DM yields varied from 2.5 to 3.0 Mg ha(-1) in the third production year. With the delay of the third harvest in autumn, the concentration of crude protein decreased to 120 g kg(-1) DM, the concentration of water-soluble carbohydrates increased to 150 g kg(-1) DM, while that of acid detergent fibre changed very little. Tall fescue has a significant yield potential in late summer and early autumn in the mid-north of eastern Canada, primarily in the first 2 production years. However, harvesting or grazing tall fescue in the week preceding or following the first killing frost will reduce persistence and spring regrowth the following year.