CHARACTERIZATION OF FORAGE YIELD OF AN ALFALFA-ORCHARDGRASS PASTURE AT DIFFERENT GRAZING FREQUENCIES AND INTENSITIES

In order to determine year-long forage yield performance of an alfalfa-orchardgrass (Medicago saliva L.-Dactylis glomerata L.) pasture subjected to different grazing frequencies and intensities, a 2 x 3 factorial arrangement of treatments (two frequencies, high and low) and three grazing intensities (severe, medium and light, with residual stubble height of 3 to 6,7 to 10 y 1110 14 cm, respectively), was evaluated under a block design with four replications in 100 m(2) plots as experimental units. 'Columbia' sheep grazed freely and no data was collected from them. The interaction among factors was not significant in any of the measured variables. Annual forage yield was higher (4 %) with the high grazing frequency, and severe grazing (3 to 6 cm) yielded more annual forage (19 %). Under frequent and severe grazing, the associated prairie can produce a higher forage yield along the year but with higher risk of weed infestation and decreased persistence. Alfalfa and orchardgrass species showed a different forage yield pattern in response to grazing intensity.