A mixture of twowinter forages: black oat (Avena strigosa Schreb. cv. Common) and Italianryegrass (Lolium multiflorum Lam. cv. Common) was introduced in a pastureof aruanagrass (Panicum maximum Jacq. cv. Aruana), grazed by sheep inan intensive production system (irrigation, fertilization and rotational stocking)with the objective of increasing the forage nutritive value during the dry winterperiod. From 04-14-00 to 01-18-01 and 06-07-01 to 02-22-02, the chemical compositionand digestibility of pre-grazing forage were evaluated in six grazing periods.A completely randomized block design with replication within blocks was used.The treatments were 1) grass alone and 2) the grass oversown with the mixtureof winter forages. Samples of pre-grazing forage mass and components (aruanagrass,black oat and Italian ryegrass) were taken to evaluate the forage botanicalcomposition, contents of crude protein (CP), neutral detergent fiber (NDF),acid detergent fiber (ADF) and lignin and in vitro dry matter digestibility(IVDMD), in the six grazing periods. In the first year, the control had a greaterCP content than oversown pasture in the third period and similar in the othersperiods, as well as greater NDF, ADF and lignin contents in the overall meanof the six grazing periods. Forage IVDMD from the two treatments were similarin all grazing periods. In the second year,the control had a greater CP contentthan oversown pasture in the fourth period and similar in the others periods,as well as greater NDF, ADF, lignin and IVDMD contents in the overall mean ofthe six grazing periods. Nitrogen fertilized and irrigated aruanagrass pasturesand aruanagrass pastures oversown with black oat and Italian ryegrass exhibitedthe same values of chemical composition and digestibility.
