C. Ducati, M.A. Neres, D.D. Castagnara, P.S.R. Oliveira, D. Weirich, G.M. Silva, and S.M.M. Sunahara. 2015. Forage potential of oat Iapar 61 alone or in association with birdsfoot trefoil. Cien. Inv. Agr. 42(3): 341-351. The objective of this study was to evaluate the structural characteristics, dry matter production, residual mass, chemical composition and in vitro dry matter digestibility of Iapar 61 black oat (Avena strigosa cv Iapar 61) pasture, both in isolation and in association with birdsfoot trefoil (Lotus corniculatus L., cv. St. Gabriel), under different forms of management in three growth cycles. A randomized block design was used with split plots in time with four treatments: conventional tillage oats, oat tillage, oats associated with birdsfoot trefoil and single birdsfoot trefoil, with three periods of evaluation and four replications. The apical meristem of oats increased from the first to the second cycle. The dry matter production of single birdsfoot trefoil was 579.65 kg on average, and the oats tillage production was 2597.78 kg. Oats exhibited high nutritional value before the first grazing in all treatments; however, at the end of its cycle, the association with birdsfoot significantly increased the crude protein content of the forage. The in vitro dry matter digestibility was similar between crops and decreased in the third cycle. Birdsfoot increased the nutritional value of oats at the end of the oat life cycle.