Date of Award:

5-2010

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Advisor/Chair:

Juan J. Villalba

Abstract

Mammals begin learning food preferences in utero and maternally mediated influences early in life help offspring develop their feeding habits. Mammals also learn by individual experience to ingest medicinal compounds such as polyethylene glycol (PEG), which attenuates the negative post-ingestive effects of tannins, a group of potentially toxic plant secondary compounds. The objective of this study was to investigate the transmission of acquired self-medicative behavior from mother to offspring using polyethylene glycol (PEG) as a medicine to relieve malaise caused by tannins. I hypothesized that: 1) mothers trained to associate the beneficial effects of PEG while consuming tannins will pass this information to their offspring, and 2) lambs will be more efficient at utilizing PEG as a medicine against tannins in the presence of mother than lambs which learn without the influence of the mother. This hypothesis was evaluated in four phases: in the first phase, a group of ewes (Experienced) was conditioned to associate the beneficial effects of PEG after consuming a tannin-containing diet. Ewes were offered a meal of high-tannin food and PEG and subsequently, the high-tannin food and grape pomace (GP) with little nutritional and no "medicinal" effects. In the second phase, the experienced and a naïve group of ewes (Inexperienced) were given a choice between the high-tannin food, PEG, and GP. In the third phase, experienced and inexperienced ewes with their naïve lambs, and the group of naïve lambs without their mothers, were exposed to the tannin-containing diet, PEG, and GP. Finally, in the fourth phase, lambs were separated from their mothers, and lambs from all groups were offered a choice between the tannin-containing diet, PEG, and GP. Lambs from experienced and inexperienced mothers showed a higher preference for PEG than lambs exposed without their mothers who tended to show a higher preference for GP. Thus, the presence of mother (experienced/inexperienced) was important for naïve lambs to learn about the medicinal benefits of PEG. This source of trans-generational knowledge could aid in maintaining the information in the herd, increasing the efficiency and reducing the risk of learning about foods and environments exclusively by individual experience.

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