Effects of a blended garlic and cinnamon essential oil extract with and without monensin sodium on the performance of grazing steers1

A series of stocker grazing experiments was conducted with the objective to determine the efficacy of supplementing growing calf diets with essential oils from garlic and cinnamon extracts (GCOE) in promoting growth on cool-season annual grasses in Arkansas (SWREC) and Oklahoma (SPER), or native rangeland at SPER. At the SWREC, steers (n = 272, BW ± SE = 209 ± 7.8 kg) grazing cool-season annual pastures were hand fed supplements containing mineral premixes that (1) were nonmedicated, (2) provided 250 mg/d of GCOE (NextEnhance, Novus International, St. Louis, MO), (3) provided 200 mg/d of monensin (MON, Rumensin, Elanco Animal Health, Indianapolis, IN), or (4) provided both 250 mg/d of GCOE and 200 mg/d of MON. In the SWREC experiment, there were no differences (P ≥ 0.13) in either BW or ADG due to GCOE, MON, or their interactions. At the SPER, steers grazing wheat pasture (n = 72, BW ± SE = 250 ± 3.9 kg) were offered ad libitum access to mineral supplements that were nonmedicated or contained 1.6 g of GCOE/kg mineral, and steers and heifers (n = 132, BW ± SE = 249 ± 4.7 kg) grazing summer native rangeland were offered ad libitum access to mineral supplements that (1) were nonmedicated; (2) provided 2.4 g of GCOE/kg; (3) provided 1.8 g of MON/kg, or (4) provided 1.8 g of MON and 2.4 g of GCOE/kg. At the SPER, there were no differences (P ≥ 0.12) in either BW or ADG due to GCOE, MON, or their interactions. In these experiments, providing GCOE or MON either by hand feeding or in self-fed mineral supplements had no effect (P ≥ 0.12) on ADG or BW of growing calves grazing cool-season annual grass pasture or summer native rangeland.