Is body surface temperature measured on the single lambs’ back a reliable indicator of the ewe-lamb bond around birth?

In extensive sheep production systems, most of the lambs' deaths are related to their low vitality at birth, and an inadequate ewe-lamb bond, leading to lambs' hypothermia. In this context, the aim of this study was to determine if lambs' rectal and body surface temperatures were related to the ewes and lambs behaviours at birth and during a separation-reunion test performed 24–36 h later. Rectal and body surface temperatures of lambs were recorded using a digital thermometer and an infrared thermal camera, respectively, and were related to several ewe and lamb behaviours. Rectal temperature was inversely related to the duration of the first suckling at birth. As for lambs' weight, body surface temperatures recorded at birth were inversely related to its latency to suckle for the first time. Body surface temperatures recorded during a separation-reunion test were positively related to the ewe-lamb distance during it. Body surface temperature recorded at birth was negatively related to behaviours recorded during the separation-reunion test, such as the number of lamb vocalizations, the ewe-lamb distance and the latency to suckle after the ewe-lamb separation. Body surface temperatures were greater after the separation-reunion test than at birth. We concluded that lambs' body surface temperatures seem to be indicators of the lambs’ vitality at birth and of the strength of the ewe-lamb bond measured one day after birth.