Behavioural reactivity of two lines of South African Merino sheep divergently selected for reproductive potential

• Published in: Applied animal behaviour science 2021-01, Vol.234, p.105209, Article 105209
• Main Authors: Bonato, Maud, Cloete, J.J.E., Kruger, A.C.M., Cloete, Schalk W.P.
• Format: Article
• Language: English
• Subjects: Behavioural tests; Production performance; Sheep; Stockman; Temperament
• ISSN: 0168-1591; 1872-9045
• DOI: 10.1016/j.applanim.2020.105209

•Behavioural reactivity of two lines of merino sheep was investigated in docility and scale tests.•No line differences were observed in the success of the docility test and the scoring in the scale test.•Low-line sheep were contained for longer and bleated more in the docility test than High-line sheep.•Rams were less stressed in both tests than ewes (lower number of bleats and urinations/defecations). The behavioural reactivity of two divergently selected lines of South African Merino sheep for an increased (HL: N = 1187) and reduced (LL: N = 285) number of lambs weaned per ewe mated was investigated using a docility test and a ‘scale’ test. The objective of this study was to determine whether these two lines, which differed significantly in terms of reproduction performance, would also react differently when exposed to novel and challenging situations. In the first test, an individual animal was moved to the test pen by an experienced handler then an unfamiliar or familiar human entered the test pen and tried to encourage the animal to move into a marked area for 3 min. The test was terminated if the animal could not be moved within 3 min, came out of the marked area or if the animal could be contained in the marked area for 30 s (successful test). The latency of the animal to enter and time contained in the square area was recorded as well as whether the animal was bleating or urinating/defecating during the test. No difference was found between production lines and handler in terms of the success of the test and latency to enter (P > 0.05). LL sheep were however contained for longer and bleated more than HL sheep (P < 0.05). Sex differences were also observed, with ewes being more difficult to successfully contain and bleating more than rams, especially when exposed to an unfamiliar human (P < 0.05). They also tended to urinate/defecate more than rams (P < 0.05). In the second test, behaviour response of animals was recorded using a 5-points score system (1 = calm; 5 = wild) while spending 30 s on a scale. We also recorded whether animals were bleating during the test. While there was no difference in average scores between selection lines (P> 0.05), inter-observer variability was observed (P < 0.05). Ewes were also observed to bleat more than rams (P < 0.05). Further research is needed to determine whether these and other behavioural tests are related to traits of economic importance in sheep.