Performance of sheep in a spatial maze is impeded by negative stimuli

Exposure to negative stimuli or stress can manifest in general changes in cognitive processing. This study aimed to investigate if a spatial maze task could be used to identify stress-induced differences in the cognitive performance of sheep. Two negative stimuli were used to test the hypothesis. For a negative pre-treatment ('dog' pre-treatment), sheep were moved individually to a holding yard at the beginning of the maze where they were exposed to a dog for 3. min, for 5 consecutive days. Alternative to the dog pre-treatment, sheep were moved in small groups to the same holding yard, for the same amount of time, where they received a feed reward ('food' pre-treatment). For a during-test stimulus, white noise was played as sheep moved through the maze ('noise' treatment). Sixty-four male castrated lambs were allocated to one of four groups: dog and noise, food and noise, dog and no noise, or food and no noise. Sheep traversed the maze on 3 consecutive days and the total time to complete the maze, the number and the duration of errors made were used to assess cognitive performance. Maze results were analysed using GLMM, LMM and linear contrasts. The noise increased both total time (140. s vs. 105. s, P= 0.043) and error time (67. s vs. 56. s, P= 0.044) on day 1. The dog pre-treatment increased error time compared to the food pre-treatment (81. s vs. 41. s, P= 0.041) and tended to increase the number of errors made on day 1 (1.5 errors vs. 1.2 errors, P= 0.057). Neither noise nor dog pre-treatment influenced cognitive performance on days 2 or 3. Results suggest that both stimuli affected cognitive performance in the maze by impeding initial problem solving. The maze used demonstrates the ability to identify differences in cognition.