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  • 1
    Electronic Resource
    Electronic Resource
    Ecological implications of condensed tannin structure: A case study (1990)
    Springer
    Journal of chemical ecology 16 (1990), S. 2381-2392 
    Details
    ISSN: 1573-1561
    Keywords: condensed tannin ; procyanidin ; blackbrush ; bitterbrush ; plant defense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Condensed tannins were isolated from bitterbnish (Purshia tridentata) and blackbrush (Coleogyne ramosissima). Structural analyses showed that both tannins were procyanidins of similar polymer length. The overall stereochemistries at C-3 and C-4, however, differed between the two tannins. These changes in stereochemistry resulted in blackbrush tannins being less preferred than bitterbrush tannins when offered to snowshoe hares (Lepus americanus). It is unlikely that differences in protein-precipitating abilities are the cause for the preference of the bitterbrush over the blackbrush tannins. Instead, we hypothesize that condensed tannins may be depolymerized and absorbed following ingestion. Differences in tannin structure can lead to different depolymerized products and rates of depolymerization, both of which may affect herbivore preferences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01017463
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  • 2
    Electronic Resource
    Electronic Resource
    How herbivores track variable environments: Response to variability of phytotoxins (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 1047-1056 
    Details
    ISSN: 1573-1561
    Keywords: Conditioned flavor aversions ; diet selection ; grazing behavior ; phytotoxins ; poisonous plants ; ruminants ; sheep ; Ovis aries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The concentration of toxins in plants can vary with plant phenology and environmental factors. Changes in toxicity may or may not be associated with changes in plant flavor. These factors may make it difficult for herbivores to avoid toxic plants. We conducted three experiments concerning animals' ability to detect toxins. In experiment 1, we examined whether animals familiar with a tastable toxin on food would adjust intake when toxin concentrations changed. Lambs were initially offered oats with either a low, medium, or high concentration of lithium chloride (LiCl; a salty-tasting toxin). Later, when all lambs were offered oats with the medium concentration of LiCl, lambs that were conditioned with the low LiCl concentration decreased intake while lambs conditioned with the high LiCl concentration increased intake. In experiment 2, we examined flavor aversions formed when animals sampled food with two flavor levels prior to illness. Lambs initially ate the same amount of barley with a low and with a high concentration of either sodium saccharin (a sweet flavor) or aluminum sulfate (a bitter flavor). Lambs then received a mild dose of LiCl. Later, when lambs were offered a choice between barley with either a low or high flavor concentration, lambs preferred the barley with the low flavor concentration. Experiment 3 examined how variable toxicity affected intake when the flavor remained constant. Lambs were initially offered oregano-flavored barley and then received a dose of LiCl. Lambs received either a medium dose, a high dose, or a dose that varied randomly among low, medium, or high amounts of LiCl. Lambs in the medium dose group ate more oregano-flavored barley at the end of the trial than did lambs in either of the other groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00987367
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  • 3
    Electronic Resource
    Electronic Resource
    Role of Toxins in Intake of Varied Diets by Sheep (2000)
    Springer
    Journal of chemical ecology 26 (2000), S. 1991-2005 
    Details
    ISSN: 1573-1561
    Keywords: Toxins ; secondary compounds ; intake ; sheep ; lithium chloride ; amygdalin ; saponin ; sparteine ; oxalate ; nitrate tannin ; toxins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Herbivores foraging on toxic plants may consume a variety of foods that contain different toxins to increase food intake and to avoid toxicosis. We studied whether lambs offered two foods, each containing a different toxin, could ingest more food than lambs offered one food with a single toxin. Thirty-two lambs were allotted to four groups that received: (1) a ration with toxin A, (2) a ration with toxin B, (3) two rations, one with toxin A and the other with toxin B, and (4) a ration with no toxins. Toxin pairs used in the study were (1) amygdalin and lithium chloride (LiCl), (2) LiCl and LiCl, (3) sparteine and saponin, (4) oxalate and nitrate, and (5) tannin and saponin. For an hour each morning, lambs were offered their ration(s) and intakes were measured. Lambs were maintained on an alfalfa pellet or grass hay diet. Each trial lasted either five or six days. Whether or not lambs ate more when offered foods with different toxins depended on the kind and amount of toxin in the food. Lambs offered rations with amygdalin and LiCl or oxalate and nitrate consumed more food than lambs offered a ration with only one of these toxins. Lambs offered rations with sparteine and saponin or tannin and saponin did not eat more food than lambs offered a ration with either saponin or sparteine or tannin alone. Nor did lambs eat more when offered two rations both containing LiCl. In all trials, lambs offered toxins showed no signs of toxicosis, and they ate less food than lambs offered rations without toxins. Our results indicate that in some cases ruminants can increase intake of toxic foods by consuming foods containing different toxins. However, currently the only way to determine how specific toxins may interact in the body to influence intake would be to conduct feeding trials using plants or ground diets that contain toxins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005565228064
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