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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2008-1493v1 87/7/2346    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Meyer, N. F. Articles by Engstrom, M. A. PubMed PubMed Citation Articles by Meyer, N. F. Articles by Engstrom, M. A.

Effect of essential oils, tylosin, and monensin on finishing steer performance, carcass characteristics, liver abscesses, ruminal fermentation, and digestibility¹

N. F. Meyer^*, G. E. Erickson^*,2, T. J. Klopfenstein^*, M. A. Greenquist^*, M. K. Luebbe^*, P. Williams and M. A. Engstrom

^* Department of Animal Science, University of Nebraska, Lincoln 68583; and DSM Nutritional Products Incorporated, Parsippany, NJ 07054

² Corresponding author: geericks{at}unlnotes.unl.edu

A feedlot (Exp. 1) experiment was conducted to evaluate the effects of an essential oil mixture (EOM), experimental essential oil mixture (EXP), tylosin, and monensin (MON) on performance, carcass characteristics, and liver abscesses. A metabolism experiment (Exp. 2) was conducted to evaluate the effects of EOM, EXP, and MON on ruminal fermentation and digestibility in finishing steers. In Exp. 1, 468 yearling steers (398 ± 34 kg initial BW) were used in 50 pens (10 pens/treatment) and received their respective dietary treatments for 115 d. Five dietary treatments were compared in Exp. 1: 1) control, no additives (CON); 2) EOM, 1.0 g/steer daily; 3) EXP, 1.0 g/steer daily; 4) EOM, 1.0 g/steer daily plus tylosin, 90 mg/steer daily (EOM+T); and 5) monensin, 300 mg/steer daily plus tylosin, 90 mg/steer daily (MON+T). Compared with CON, steers fed MON+T had decreased DMI (P < 0.01), and steers fed EOM+T and MON+T had improved G:F (P 0.02). Average daily gain was not different among treatments (P > 0.58). There was a trend (P = 0.09) for a treatment effect on 12th-rib fat thickness, which resulted in a significant increase in calculated yield grade for the EOM+T treatment. No other carcass characteristics were affected by treatment (P 0.10). Prevalence of total liver abscesses was reduced for steers fed tylosin compared with no tylosin (P < 0.05). In Exp. 2, 8 ruminally fistulated steers (399 ± 49 kg initial BW) were assigned randomly to 1 of 4 treatments in a replicated 4 x 4 Latin square designed experiment. Treatments were 1) CON, 2) EOM, 3) EXP, and 4) MON with feeding rates similar to Exp. 1. There were no differences in DMI, OM intake, and apparent total tract DM or OM digestibilities among treatments (P > 0.30). Feed intake patterns were similar among feed additive treatments (P > 0.13). Total VFA (P = 0.10) and acetate (P = 0.06) concentrations tended to be affected by treatment with EOM numerically greater than CON. Average ruminal pH ranged from 5.59 to 5.72 and did not differ among treatments. Addition of a EOM or monensin to a diet containing tylosin improves G:F, but little difference was observed in metabolism or digestibility.

Key Words: cattle • essential oil • metabolism • monensin • performance • tylosin