The capability of several toxic plants to condition taste aversions in sheep

Modeling the effects of low toxin levels in food on feeding: dose-dependent reduction of fluid intake by low levels of lithium chloride

The present study examined the dose related effects of low levels of the toxin, LiCl, on the ingestion of a palatable sucrose plus salt solution. Over five days (acquisition phase) rats were presented with a 0.3M sucrose solution containing one of the following salt combinations: 0.12 M NaCl (n=10 negative control group); 0.005 M LiCl+0.115 NaCl (n=10); 0.01 M LiCl+0.11 NaCl (n=10); 0.015 M LiCl+0.105 M NaCl (n=10); 0.02 M LiCl+0.10 M NaCl (n=10); and 0.12 M LiCl (n=8 positive control group). During an extinction phase (5 days), all rats were presented with 0.3M Sucrose+0.12 M NaCl solution. Fluid intake levels and number of licks were quantified on each day. At low LiCl concentration levels rats exhibited a dose related reduction in amount consumed and number of licks of the sucrose plus salt solutions. This toxin related suppression of fluid intake and licking rapidly dissipated during the extinction phase. The present findings support the hypothesis that rats use a behavioral tolerance mechanism to regulate their intake of foods containing low levels of toxins.

Conditioned food aversion to Ipomoea carnea var. fistulosa induced by Baccharis coridifolia in goats

Baccharis coridifolia is a plant that induces strong conditioned food aversion in ruminants. This research aimed to induce a conditioned food aversion to Ipomoea carnea var. fistulosa in goats, using B. coridifolia as an aversive agent, and to compare the aversion induced by this plant with the aversion induced by lithium chloride (LiCl). Thirteen goats were allotted into two groups: Group 1 with six goats was averted with 175mg/kg of body weight of LiCl and Group 2 with seven goats was averted with 0,25g/kg of bw of dried B. coridifolia. All goats were averted on day 1 after the ingestion of I. carnea. The aversion procedure with LiCl or B. coridifolia in goats from Groups 1 and 2, respectively, was repeated in those goats that again consumed the plant during tests on days 2, 3, and 7. The goats of both groups were challenged in pens on 23 and 38 days after the last day of aversion and challenged in the pasture on days 11, 15, 18, 20, 22, 25, 27 and 29 after the last day of aversion. After this period goats were challenged every 15 days on pasture until the 330º day after the last day of aversion (7th day). Two goats from Group 1 ingested I. carnea on the first day of the pasture challenge, 4 days after the last day of aversive conditioning in the pen. In addition, another goat in Group 1 started to consume the plant on day 18, and other two goats ate it on day 20. One goat in Group 1 that had never eaten I. carnea died on day 155. One goat from Group 2 started to ingest I. carnea on the first day of the pasture challenge, and a second goat started to consume this plant on day 182. At the end of the experiment, on day 330, the other five goats averted with B. coridifolia remained averted. These results suggest that B. coridifolia or an active compound from the plant could be used to induce aversion to toxic plants. Using B. coridifolia would be cheaper and, particularly in flocks with large number of animals, possibly easier than using LiCl, which requires the use of oral gavage and qualified personnel for its implementation.