Abstract The objective of this study was to evaluate the impacts of castor meal, a by-product of the biodiesel industry, on growth performance and feeding behavior of heifers in a pasture production system in Northeast Brazil. Forty Holstein × Zebu crossbred heifers with an initial body weight of 257±26 kg were kept on a Brachiaria decumbens pasture under continuous grazing. The experiment lasted 140 days and was conducted in a completly randomized design with five levels of replacement of soybean meal with castor meal (0, 200, 500, 750, and 1000 g/kg of dry matter) in the supplements. Intake, digestibility, feeding behavior, performance, and carcass characteristics were evaluated. The total intakes of dry matter (DM), crude protein (CP), organic matter (OM), ether extract, and total digestible nutrients (TDN) decreased as the castor meal levels were increased. The digestibility coefficients of DM, CP, OM, and TDN decreased as the levels of castor meal in the supplement were increased. The castor meal levels in the supplement did not affect final body weight, average daily gain, feed conversion, hot carcass weight, or carcass dressing of the heifers. The use of supplements containing up to 1000 g/kg DM castor meal replacing soybean meal reduced the DM intake but did not change the average daily gain and feed efficiency of the heifers. Thus, the use of castor meal is a recommendable strategy to reduce production costs in a beef cattle grazing system.