Maternal influence on feeding site avoidance behaviour of lambs

Abstract

Ewes can play a critical role in moulding habitat preferences of their daughters. Little is known, however, about how feeding site preferences of lambs can be modified by manipulating the behaviour of their dams. We conducted an experiment with sheep to investigate the influence of shock-trained mothers and early-life aversive experiences on the feeding site choices of lambs. Twelve ewes with their 6-week-old lambs were exposed to an experimental arena with artificial safe and unsafe feeding sites (SFS, UFS) each of which consisted of a group of 12 bowls containing either high or moderate quality food. The bowls in UFS were surrounded by visual cues (traffic cones) and contained rolled corn grain (high quality food). Bowls in SFS were not surrounded by visual cues and contained a mixture of Bermuda grass and alfalfa hay (moderate quality food). Four ewe/lamb pairs were randomly assigned to each of the following treatments: (a) no aversion training to neither ewe nor lamb (control); (b) shock stimulation to train the ewe but not the lamb (ES) to avoid UFS; or (c) shock stimulation to train the lamb but not the ewe (LS) to avoid UFS. Lambs remained with their mothers throughout training, testing, and initial extinction trials. Mothers were then removed, and additional extinction trials were conducted with weaned lambs alone. Ewes and lambs that were trained with shock learned to avoid UFS. ES ewes avoided UFS throughout the study and their lambs tended to spend less time in UFS even after their mothers were removed compared to LS and control lambs. LS lambs avoided UFS until shock was removed; after that they tended to enter UFS more often than ES and control lambs. ES pairs and lambs (after ewes were removed) consumed less food in UFS and spent less time feeding versus standing compared to ewes and lambs on the other treatments. Naïve ewes appeared to induce shock-trained lambs to re-enter the unsafe feeding site; shock-trained ewes, on the other hand, appeared to induce naïve lambs to avoid feeding in a high quality feeding site that they would have possibly otherwise preferred. Maternal influence persisted after lambs were weaned.