Feeding preferences of experienced and naïve goats and sheep for the toxic plant <italic>Ipomoea carnea</italic> subsp. <italic>fistulosa</italic>

Abstract

<p><bold>Ipomoea carnea</bold> is a toxic plant that grazing goats and cattle may learn to ingest with repeated exposure. The objective of this study was to evaluate the feeding preferences of experienced and non-experienced (naïve) goats and sheep for<bold> I. carnea.</bold>The study used 3 groups of 5 goats (Group 1, experienced that were previously poisoned by the plant; group 2, naïve; Group 3, experienced eaters, composed of animals adapted to eat the fresh plant) and 2 groups of sheep (group 4, experienced that were previously poisoned by the plant; and group 5, naïve). For the test, the animals were placed daily for 10 minutes and 4 days in a rectangular stall (5x7m) with 4 feeders, each with 200g of a different food (<bold>Ipomoea carnea</bold>, commercial concentrate food, recently harvested green grass (mainly <bold>Brachiaria</bold> spp.), and <bold>Cynodon dactylon</bold>hay. The intake of concentrate food was significantly higher (P<0.05) than the consumption of green grass, hay and <bold>I. carnea</bold>. In a second 4 day trial, in which the commercial concentrate food was replaced by freshly harvested <bold>Amorimia septentrionalis</bold>, the ingestion of green grass (<bold>Brachiaria</bold> spp.) was significantly higher (P<0.05) than the consumption of other foods. In both trials there was no significant difference in food consumption between eaters and naïve animals. The results suggest that experienced or naïve sheep and goats do not prefer <bold>I. carnea</bold> when it is offered with other foods or forages, suggesting that animals will avoid the plant and not become poisoned if other food options are available.</p>