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United States Department of Agriculture

Agricultural Research Service

Research Project: Understanding and Mitigating the Adverse Effects of Poisonous Plants on Livestock Production Systems

Location: Poisonous Plant Research

Title: Conditioning food aversions to Ipomoea carnea in sheep

Authors
item Adrien, Maria -
item Gardner, Dale
item Pfister, James
item Marcolongo-Pereira, Clairton -
item Riet-Correa, Franklin -
item Schild, Ana -

Submitted to: Electronic Publication
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 28, 2013
Publication Date: N/A

Interpretive Summary: Ipomoea carnea is a toxic plant in Brazil that often poisons sheep. Conditioned food aversion may be a tool to reduce intoxication problems in grazing sheep. Both lithium chloride (LiCl) and the toxic plant Baccharis coridifolia were used to condition aversions in sheep fed Ipomoea in pens and in a pasture setting. Neither treatment was completely successful at conditioning strong and persistent aversions in sheep. The transient and incomplete aversions indicates that neither aversive agent will condition aversions sufficient to cause sheep to avoid the plant in subsequent encounters.

Technical Abstract: Ipomoea carnea is a toxic plant in Brazil that often poisons sheep. Conditioned food aversion may be a tool to reduce intoxication problems in grazing sheep. Fifteen sheep were adapted to consume I. carnea for 36 days. Subsequently sheep were randomly divided into three groups of five sheep each. Group 1 was averted with LiCl, group, Group 2 was averted with Baccharis coridifolia, and Group 3 was the control group. The sheep were periodically tested by exposing to I. carnea in the pasture and in individual pens up to the 74th day after the first day of aversion. On the 14th and 19th days the number of sheep in Group 3 that consumed I. carnea was significantly higher than the number of sheep that consumed I. carnea in Groups 1 and 2 (P=0.004 and P=0.0004, respectively). On day 24 the number of sheep that consumed I. carnea was significantly higher in Group 3 than Group 1 (P=0.004). After the challenge on the 29th day no significant difference (P>0.05) was observed in the consumption of the plant among the three groups. On day 7 of the aversion period control sheep (group 3) consumed more I. carnea than did the sheep from Groups 1 and 2 (P=0.0002 and P=0.01, respectively). After this period there was no difference in the amount of I. carnea ingested by the sheep in other individual challenges. The maximum time spent by the sheep grazing I. carnea was 2.4%±1.6% of the total grazing time and no difference was observed among the groups. I. carnea was never consumed avidly by the experimental sheep, and some LiCl animals did not learn to avoid the plant on a consistent basis. Conditioning an incomplete aversion indicates that neither LiCl or B. coridifolia will work with sheep in field settings to reduce or eliminate consumption of I. carnea.

Last Modified: 7/30/2014
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