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The effect of 1-h temporary sensory separation of ewes from lambs on the stress-related behaviors and hormones of Small-tailed Han ewe

Chengquan Han , Yueshang Wang, Min Li, Fukuan Li, Zhennan Wang, Yan Yang, Hui Wang, Shenjin Lv

Abstract

Context: Different individuals within a group can form strong links through auditory, visual, and tactile senses. Temporarily separating sheep into sub-flocks, although not involving complete social isolation of individuals, can be stressful, especially when ewes are separated from lambs. Aims: This study aimed to explore the effects of 1-h temporary ewe-lamb sensory separations on stress-related behaviors during separation, as well as its effect on stress-related hormones of ewes. Methods: Small-tailed Han ewes were randomly assigned to four groups (6 each): the auditory + visual + tactile separation (A+V+T group), visual + tactile separation (V+T group), tactile separation (T group), and the control (C group). Then the ewes were separated from their lambs for 1 h on postnatal days 14, 21, 28, 35 and 42. Ewe behaviors during the separations were observed using focal animal sampling methods. Key results: Results showed that the separated ewes (A+V+T, V+T, and T groups) spent more time looking and exploring and less time lying (P < 0.05). Ewes show more exploring behavior in T group (P < 0.05). Ewes that give birth to two lambs showed more urinating behavior (P < 0.05). There was no significant difference in the level of stress-related hormones in ewes among the four different separation method groups (A+V+T, V+T, T, and C groups). Conclusion: One-hour ewe-lamb sensory separation affected the stress-related behaviors of Small-tailed Han ewes during separation, but it did not cause remarkable difference in stress-related hormones in ewes after the separation. Ewes showed more obvious exploring or urinating behavior when they were separated by lack of tactile contact only with lambs, or when ewes give birth to two lambs. Implication: It suggests that when ewes are temporarily separated from their lambs, trying to let the ewes avoid hearing and seeing the lambs may partially reduce their stress response, thereby improving the welfare of Small-tailed Han ewes. The findings of this study also suggest that ewes with twin lambs may be more stressed to the temporary ewe-lamb separation, which provides a new perspective for further studies on the effect of litter size on the ewe-lamb bonding in the future.

AN24242  Accepted 12 September 2024

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