GRAZING SCHEDULE EFFECT on FORAGE PRODUCTION and NUTRITIVE VALUE of DIVERSE FORAGE MIXTURES

Authors: DEAK, ATILA - MONSANTO INC; HALL, MARVIN - PENN STATE UNIV; Sanderson, Matt

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2008
Publication Date: 2/1/2009
Citation: Deak, A., Hall, M., Sanderson, M.A. 2009. GRAZING SCHEDULE EFFECT on FORAGE PRODUCTION and NUTRITIVE VALUE of DIVERSE FORAGE MIXTURES. Agronomy Journal. 101(2):408-414.

Interpretive Summary: Sustained forage production is a key element for successful livestock production in grazing systems. In this study, we evaluated the effects of two grazing schedules on forage production, nutritive value, and botanical composition of grass monocultures, simple grass-legume combinations, and more complex mixtures of 3 to seven forage species under rotational grazing. Basing grazing management on the height of the pasture canopy produced greater forage yields than grazing based on plant morphology. The addition of legumes to pure grass stands improved nutritive value, forage production, and reduced use of nitrogen fertilizer. Mixture complexity improved forage production in a dry year, but not under more favorable weather conditions. More importantly, variability in forage yield decreased with increasing mixture complexity. The use of complex mixtures composed of forage species adapted to the environment can be an alternative to binary grass-legume mixtures or grass monocultures in drought-prone environments where consistency in DM production is more important than top forage productivity.

Technical Abstract: Sustainability of forage production in the Northeast USA depends on suitable forage species for the environment and grazing management. The use of multispecies mixtures may increase yield and sustain forage production; however, we have no information on how grazing management affects the productivity of mixtures. A grazing experiment was carried out during 2005 and 2006 near State College, PA to evaluate to evaluate several combinations of grasses, legumes, chicory (Cichorium intybus L.) for their botanical composition, nutritive value, and production under two grazing managements. Field plots of each mixture were grazed according to canopy height (HEIGHT treatment; when the canopy reached 25 cm) or morphology [MORPHOLOGY treatment; when alfalfa (Medicago sativa L.) reached bud stage]. Grazing frequency had little effect on botanical composition. Legume and weed content decreased as the number of forage species in the mixture increased. The HEIGHT grazing treatment produced 30% more forage (6 777 kg ha**-1) than the MORPHOLOGY grazing treatment (5 222 kg ha**-1). Dry matter yield of the five- and seven-species mixtures was stable during the contrasting weather of 2005 and 2006. The HEIGHT grazing treatment produced forage of better nutritive value compared with the MORPHOLOGY grazing treatment at first harvest in both years. Nutritive value increased with more forage species in the mixture. The use of complex mixtures composed of forage species adapted to the environment can be an alternative to binary grass-legume mixtures or grass monocultures in variable environments where consistency in forage production is more important than top forage productivity.