Effects of mowing regimes on forage yield and crude protein of Leymus chinensis (Trin.) Tzvel in Songnen grassland

Forage dry matter (DM) yield and its nutrient content are important in livestock nutrition; however, they have distinct, even opposite responses to mowing regimes. To optimize forage resources, two independent field experiments were conducted to determine effects of initial mowing time (15-day intervals from May 15 to September 1) and mowing frequency (one to five times per year) on DM yield and nutritive value of Leymus chinensis (Trin.) Tzvel. The greatest cumulative DM yield (cDMY), pre-mowing crude protein yield (pCPY) and cumulative crude protein yield (cCPY) were attained when initial mowing occurred from July 15 to August 15. The crude protein (CP) concentration of pDMY was higher, whereas fiber concentrations were lower, when initial mowing was from May 15 to June 15, with opposite results when the initial mowing was delayed (July 1 to September 30). When mowing three times annually, cDMY and cCPY of L. chinensis were higher (p < .05) than with less frequent mowing. With more than three mowings, accumulated CP yield of L. chinensis was not significantly affected. With four or five yearly mowings, accumulated DM yield of L. chinensis decreased significantly compared to mowing one to three times. In conclusion, based on DM yield and nutritive value, the optimal initial mowing date ranged from July 15 to August 15, whereas optimal mowing frequency was three times yearly.