The aim of the analysis systems for rearing of beef heifers in black oats (Avena strigosa Schreb) and annual ryegrass (Lolium multiflorum Lam) pasture was to determine animal performance and economic relationships. Data were analyzed from four grazing trials performed at the Federal University of Santa Maria, RS. Production costs, animal production and gross margin were evaluated. The trials were conducted from 1998 to 2001. The feeding systems were YEAR 1: STP- animal supplementation during entire pasture cycle; SAS - supplementation of animals until September; SS - no supplementation; YEAR 2: energy supplementation levels of 0, .7, and 1.4% of live weight (LW); YEAR 3: AAS- oats + ryegrass + supplementation; AAN - oats + ryegrass + 300 kg/ha of nitrogen; AAL - oats + ryegrass + arrowleaf clover (Trifolium vesiculosum Savi); YEAR 4: DFB - low forage availability; DFA - high forage availability; DFBS - low forage availability and supplementation; DFAS - high forage availability and supplementation. Beef heifers of the Charolais breed and their crosses with Nellore with initial age of eight months were used. The live weight (LW) gain and feeding systems production costs ranged from 324 to 671 and from 267 to 632 kg/ha of LW, respectively. The greater gross margin was obtained in 1999, 148 kg/ha of LW, only in pasture and 137 kg/ha of LW, with supplementation. The price paid for kg of supplement must be from .05 to .07 kg of LW to be economically viable in relation to the use of exclusive pasture.
annual ryegrass; economic return; oats; rearing of heifers; supplementation
