Grazing schedule effect on forage production and nutritive value of diverse forage mixtures
The use of complex mixtures (mixtures of more than three species) may increase yield of pastures; however, we know little about how grazing management affects the productivity of mixtures. A grazing experiment was performed during 2005 and 2006 near State College, PA, to compare mixtures of grasses, legumes, and chicory (Cichorium intybus L.) for their botanical composition, nutritive value, and forage production under two grazing schedules: when the sward reached 25 cm in height (sward height schedule, SH) or when alfalfa (Medicago sativa L.) reached the bud stage (morphology or MP schedule). The SH schedule produced 30% more dry matter (DM) than the MP schedule averaged for 2 yr. Forage yield of the five-species (6427 kg ha–1 in 2005 and 6624 kg ha–1 in 2006) and seven-species (6816 kg ha–1 in 2005 and 6772 kg ha–1 in 2006) mixtures was stable during the contrasting weather of 2005 and 2006. Grass monoculture with N and simple mixtures (two species, grass–legume) produced 989 kg ha–1 more DM than the complex mixtures in 2006 when weather conditions were favorable. The SH schedule produced forage of better nutritive value compared with the MP schedule at first harvest in both years [20 g kg–1 less acid detergent fiber (ADF) in 2006; 25 g kg–1 in 2005, 53 g kg–1 in 2006 more neutral detergent fiber (NDF); 21 g kg–1 in 2005, 30 g kg–1 in 2006 more crude protein (CP); and 33 g kg–1 in 2006, 53 g kg–1 more in vitro true dry matter digestibility (IVTDMD)]. Complex mixtures of forage species provide more consistent yields of DM than binary grass–legume mixtures or grass monocultures in variable environments.