It was evaluatedthe shading effect induced by two tree densities of a ten-year-old slash pine(Pinus elliottii Engelm.) forest, and at full sun, on forage dry matteryield and nutritive value of three cool-season annual grasses. Treatments werea combination of two main factors: a) three light conditions induced by twotree densities (333 e 555 stems/ha) and at full sun; b) three cool-season annualforage grasses: Italian ryegrass (Lolium multiflorum Lam.), common oat(Avena sativa L.) cv. Fapa-2, and black-oat (Avena strigosa Schreb.).A split-plot experimental design, with three replications, was used. The mainplots were the light conditions affected by tree density and the subplots werethe different forage species. Sowing dates were from July 25 to August 5, 2005and April 26 and 27, 2006. In order to determine forage DM yield, plants werehand-clipped at the vegetative stage (104 days after sowing, in 2006) and atfull bloom (132 and 170 days, in 2005 e 2006, respectively). Forage nutritivevalue was accessed by determining crude protein (CP) concentration and invitro organic matter digestibility (IVOMD). Results showed that when plantswere at the full bloom stage and under moderate shading, forage DM yield wasreduced by 57%, forage CP content was increased by 2,3%, and IVOMD was raisedby 5,5%, compared to plants at full sun. In terms of their potential utilization,common oat and black-oat show promise for regional silvopastoral systems insouthern Brazil.
