Behavioral and physiological responses to tail docking with rubber rings in weaned twin lambs housed with either docked or undocked siblings

Abstract

The aim was to compare the behavioral and physiological responses to tail docking with rubber rings in weaned twin lambs housed with either their docked or undocked sibling, or with familiar lambs that were either docked or undocked. Weaned 4-month-old East Friesian and Finnish Landrace twin lambs were tail docked with rubber rings and pair-housed with: (1) undocked sibling (UND-SI, n=10); (2) docked sibling (DOC-SI, n=10); (3) undocked familiar lamb (UND-FL, n=11); or (4) docked familiar lamb (DOC-FL, n=11). Lambs' behaviors were continuously recorded for 17 min after tail docking. Heart rate, rectal temperature, and eye surface temperatures were recorded immediately before tail docking and 40 min after, and the percentages of change were determined by considering the initial value as 100%. The experimental design was a 2 x 2 factorial arrangement. The factors were the type of companion [two levels: the sibling or a familiar lamb] and the condition of the companion lamb [two levels: docked or undocked]. Tail docked lambs housed with UND-SI reduced the number of times that the lamb wagged its tail (UND-FL vs UND-SI: P=0.004) and displayed agonistic behaviors (head-butting and pushes) (UND-FL vs UND-SI: P=0.003). However, when the companion lamb was the DOC-SI, the number of times the lamb wagged its tail increased (DOC-FL vs DOC-SI: P=0.0001). Lambs tail-docked in the companion of the DOC-SI increased the variation of the eye surface temperature (DOC-FL vs DOC-SI: P=0.002). Lambs housed with their SI after tail docking reduced the number of vocalizations and increased restlessness and the number of escape attempts (P<0.0001, P=0.05, P=0.05 and P=0.04, respectively). Housing tail-docked lambs with their UND-SI may constitute an effective strategy for alleviating stress and pain responses associated with tail docking in twin lambs. Conversely, housing tail-docked lambs with their DOC-SI exacerbates these responses.