Effects of Merino flock size, paddock complexity and time of day on response to trained leaders

Abstract

This study examined if Merino sheep trained to respond to a combined visual and auditory stimulus could influence the movement of naïve Merino sheep flocks when the stimulus was activated. Trained Merino ewes were mixed with naive ewes and wethers in three groups of different sizes. Group ratios were (trained:naïve) Small Mob (SM) 1:5 ratio (n = 18), Medium Mob (MM) 1:10 (n = 33) and Large Mob (LM) 1:15 (n = 48). These groups were tested in 2 phases of increasing complexity. The first phase examined the responses of the different sized flocks (SM, MM and LM) to leader-initiated movement in 3 visually open paddocks (OP) during morning and afternoon grazing. The second phase examined the response of two flocks (SM and LM) at similar times but in 3 visually complex paddocks (CP). Animal groups were tested on 1 day per week in each paddock at pseudo random times. One hundred percent of the SM, 73.5% of the MM and 70% of the LM approached within 6 m of the stimulus in the OP tests. In the CP 100% of the SM and 56.5% of the LM approached the stimulus. The LM's proximity to the stimulus in some of the CP tests was more than 6 m, however, it was not significant compared to the other CP or OP tests. Sixty seven percent of the SM animals and 33% of the LM of naïve sheep were observed to initiate movement toward the stimulus after the 6 tests in phase one. At the end of the first phase of testing the proportion of naïve sheep observed to be eating the previously unknown grain (lupins) was SM 73%, MM 60% and LM 36%, suggesting that naïve sheep will learn to eat a novel grain by following trained animals. Sub-grouping of the flock in this study was not a hindrance to flock movement. This study demonstrated that sheep trained to respond to a stimulus do provide leadership when mixed with naive sheep flocks causing a flock to rapidly change position to congregate around an activated stimulus. These findings suggest that trained animals could be used to manipulate animal movement for farm management purposes.