Two experiments were conducted at the University of Arkansas Southwest Research and Experiment Station (Hope, AR) and Livestock and Forestry Branch Station (Batesville, AR) in northern Arkansas. Growing beef calves (n = 96 steers at the Hope site and 48 steers and 48 heifers at the Batesville site, BW = 215 ± 14.5) grazed 0.8 ha warm-season grass based pastures (n = 24/site, predominantly bermudagrass) during a 56-d summer grazing study to determine the effects of supplementation of growing steers grazing warm-season perennial grass pastures with Lasalocid via self-limited block (Bovatec 2.2 Block, Zoetis Animal Health, Inc.) on growth performance. Pastures were stocked with 4 calves/pasture with 24 total pasture replicates/treatment. Because of drought conditions this study was initiated on June 12 and terminated on August 8 at the Batesville site and was initiated on June 27 and terminated on August 22 at the Hope site. At the Hope site, lack of grazable forage made it necessary to offer grass hay (10% CP and 55% TDN) and soybean hulls at 2 lb/head/d to all pastures for the duration of the study. Beginning and ending weights were collected full on 2 consecutive days, and interim weights were collected full on 28-d intervals. Calves in each pasture were offered free-choice access to either a non-medicated control trace mineralized salt block (Control) or Bovatec 2.2 block (Bovatec). Daily block intakes at the Hope site averaged 12 ± 8.1 g/calf with an average Bovatec dose of 59 ± 39 mg/head/day. At Batesville, daily intake of control averaged 28 ± 12 g/calf and intake of Bovatec averaged 20 ± 5.3 g /head/day (supplying 100 ± 25 mg Bovatec). There was no treatment × site interaction (P = 0.44) for performance in this study. At the end of the study there was no difference (P ≥ 0.16) between Control and Bovatec treatments for BW (267 vs 269 ± 3.9 kg, respectively) or ADG (0.75 vs. 0.81 ± 0.0435 kg/d, respectively). The results of this study indicate that Bovatec offered in a self-fed trace mineralized salt block supplement did not supply a large enough dose of lasalocid to increase growth rate of beef calves grazing warm-season grass pastures.