Submitted to: Small Ruminant Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/28/2006
Publication Date: 9/10/2007
Citation: Estell, R.E., Fredrickson, E.L., Anderson, D.M., Remmenga, M.D. 2007. Effects of eugenol, alpha-terpineol, terpin-4-01, and methyl eugenol on consumption of alfalfa pellets by sheep. Small Ruminant Research. 73:272-276. Interpretive Summary: Encroachment of shrubs into arid grasslands is of concern to both livestock producers and ecologists. Shrubs often contain chemicals that cause them to be unpalatable to livestock and wildlife. We are exploring the relationship of volatile plant chemicals and shrub consumption by herbivores. Our previous work revealed that preference of livestock for tarbush varied considerably from plant to plant, and volatile leaf surface chemicals were partly responsible for that variability. In this study, we applied four chemicals contained in tarbush to alfalfa pellets and fed themn to lambs to determine if they affect intake when applied individually. None of the compounds tested (eugenol, '-terpineol, terpin-4-ol, or methyl eugenol) reduced intake in this study, and therefore do not appear to be related to the avoidance of shrubs by livestock. Information on the compounds that control intake will ultimately provide us with mechanisms to alter the amount of a particular plant species consumed by livestock.
Technical Abstract: Many secondary compounds are typically present in unpalatable shrubs on rangelands in the western United States. However, the relationship between intake by livestock and concentration of individual chemicals has been examined for very few of these compounds. Four experiments were conducted to examine effects of individual volatile compounds on intake of alfalfa pellets by lambs. Forty-five lambs (9 lambs/treatment) were individually fed alfalfa pellets with eugenol, '-terpineol, terpin-4-ol, or methyl eugenol applied at one of five concentrations in an ethanol carrier. Treatments were multiples (0, 0.5, 1, 2, and 10X) of the concentration (X) of each compound on the leaf surface of Flourensia cernua. Treatment solutions were sprayed on alfalfa pellets (0.64 kg.lamb-1.d-1, DM basis), and consumption was measured during a 20-min interval for five days. A day effect (P < 0.001 for both linear and quadratic contrasts) was detected for intake in all four experiments, but no day x treatment interactions were observed (P > 0.05). The day effect was generally due to lower intake on day 1, except for the methyl eugenol experiment, in which lambs consumed more pellets on day 1. No treatment effects were observed (P > 0.05) for any of the four chemicals tested; thus, eugenol, '-terpineol, terpin-4-ol, and methyl eugenol were not related to intake of alfalfa pellets by lambs under the conditions of this study.