|HENSLEE, DILLON - University Of Idaho|
|YELICH, JOEL - University Of Idaho|
|ELLISON, MELINDA - University Of Idaho|
|Taylor, Joshua - Bret|
Submitted to: Translational Animal Science
Publication Type: Proceedings
Publication Acceptance Date: 5/21/2019
Publication Date: 12/16/2019
Citation: Henslee, D., Yelich, J., Ellison, M., Taylor, J.B. 2019. Aversion to phenylthiocarbamide in mature Targhee and Rambouillet rams. Translational Animal Science. 3(1):1749-1753. https://doi.org/10.1093/tas/txz080.
Interpretive Summary: Not required.
Technical Abstract: Shrub encroachment on grasslands is a worldwide issue and sheep are a potential tool for mitigating shrub encroachment. However, many shrubs contain bitter-tasting compounds that may detour grazers. We hypothesized that sheep could detect (i.e., taste) bitter-tasting compounds and the sensitivity to these compounds would vary from animal to animal. The objective of this study was to determine whether sheep could detect the bitter-tasting compound phenylthiocarbamide (PTC), and if so, what PTC concentration would elicit an avoidance response. Using a crossover study design, mature Rambouillet and Targhee rams (n = 30) were subjected in randomized order to various PTC concentrations mixed in the drinking water (PTC-solution). In trials 1 and 2 (n = 15/trial), 0.20, 0.56, 1.57, 4.39, and 12.39 mM and 0.20, 0.43, 0.94, 2.03, and 4.39 mM of PTC were tested, respectively. On test days, PTC-solution (trial 1: 1.5 kg; trial 2: 3.0 kg) and water (same amounts) were offered for ad libitum intake in a side-by-side presentation for 1 h in trial 1 and 2 h in trial 2. Each test day was followed by a rest day where PTC-solution was replaced with water to limit potential carry over effects into the next test day. Consumption of PTC-solution for each PTC concentration was expressed as the percentage of PTC-solution intake of total morning fluid intake. Intake of PTC-Solutions decreased (P < 0.01) with increasing concentrations PTC in both trials. The greatest decrease (P < 0.01) in percentage of PTC-solution intake occurred between 1.57 and 4.39 mM (58%) for trial 1 and 2.03 and 4.39 mM (72%) for trial 2. This research suggests rams could taste the PTC, and the concentration at which PTC-solution was avoided varied across rams. It may be possible to select sheep, based on demonstrated avoidance of PTC, for targeted grazing applications to manipulate vegetation towards range management goals.