Effects of functional oils and monensin on cattle finishing programs1

The use of functional oils (FO; Essential) and ionophores on cattle feedlot performance, carcass characteristics, and economic analysis was evaluated. Angus and Angus crossbred steers were assigned to 5 treatments: control (CON); monensin (MON); monensin + FO low dosage (MON+FL); FO low dosage (FL); and FO high dosage (FH; n = 48/treatment; 6/rep). Daily DMI was not affected (P > 0.05) by FO, and MON improved ADG and G:F when compared with FL and FH (P < 0.05). Dressing percentage for the FH treatment was larger than for MON and FL (P < 0.05). Longissimus muscle area of FH cattle was the largest of all treatments and differed from that of MON (P < 0.05). Backfat thickness was not different (P > 0.05) among treatments. Cattle on the MON+FL treatment yielded the best cutability and differed from MON (P < 0.05). Quality grade was not different (P > 0.05) among treatments. Diets with FO increased the percentage of Choice and Prime carcasses, and FH yielded the largest percentage of Prime grade carcasses, differing from CON and MON+FL (P < 0.05) but not from MON and FL (P > 0.05). Sensory panel evaluations were unaffected by treatments (P > 0.05). Using actual costs and prices, profitability was numerically highest for MON+FL. In annual and seasonal price scenarios, profitability favored FH. Carcass price provided the greatest effect on profitability. Thus, the use of FO may provide a viable alternative to ionophores in feedlot cattle.