Neill, C.R.Groesbeck, C.N.Lawrence, K.R.Hastad, C.W.Gottlob, R.O.Hildabrand, B.M.Nelssen, Jim L.Tokach, Michael D.Goodband, Robert D.DeRouchey, Joel M.Dritz, Steven S.2009-10-292009-10-292009-10-29http://hdl.handle.net/2097/1954A total of 224 nursery pigs (PIC L 327L × C22) initially 12.9 ± 3.0 lb and 21 d of age were used in a 28-d feeding trial. The objective of our study was to evaluate the effects of oregano oil, with or without an in-feed antimicrobial. Oregano oil is a plant extract derived from the Greek herb, Origanum vulgare. It has been speculated to have antimicrobial-like activity. There were four dietary treatments in a 2 × 2 factorial. Diets consisted of a negative control (without an antibiotic or oregano oil), the control diet plus neomycin/oxytetracycline (140 g/ton), the control diet plus oregano oil, or the control diet with both neomycin/ oxytetracycline and oregano oil. The oregano oil (5%) was added to an inert carrier (95%) to make a premix that was added to the diet at 2 lb/ton in phase 1 (d 0 to 14) and 1 lb/ton in phase 2 (d 14 to 28). During the 28-d trial, neomycin/oxytetracycline improved ADG, ADFI and F/G. Pigs fed dietary treatments containing neomycin/oxytetracycline had the heaviest average weights at the end of the trial. Adding oregano oil to nursery pig diets did not improve ADG, ADFI, or F/G during the 28-d trial.Nursery pigsNeomycin/OxytetracyclineSwineOreganoPigsConference paper