ResearchBehavior of lambs at different ages during brief periods of increased sensorial isolation from their mothers

To determine the behavior of different-aged lambs during short periods of increased sensorial isolation from their mothers, 6S0 ewe-lamb pairs were randomly assigned to one of the following groups: “C,” intact lambs that remained with their mothers; “A,” lambs with restricted auditory capacity; “A+V,” lambs with restricted auditory and visual capacities; “A+V+W,” lambs with restricted auditory and visual capacities plus separation from their mothers by an open wire mesh; and “A+V+S,” lambs with restricted auditory and visual capacities plus separation from their mothers by a solid wall. These treatments were repeated in the same animals when lambs were 3 (G3), 10 (G10), and 20 (G20) days old. The behavior of lambs was recorded during each 15-minute separation period, and data were examined using covariance analysis to determine differences for repeated measures over time. In general, after the physical separation from the ewes (A+V+W and A+V+S groups), lambs emitted more vocalizations (3, 10, and 20 days old) and displayed more frequent urination (3 days old), exploration of objects (20 days old) and conspecifics (3 and 20 days old), escape attempts (A+V+W at 10 and 20 days of age; A+V+S at 20 days old), or walking (A+V+W at 10 and 20 days of age; A+V+S at 3, 10 and 20 days old) and lying down (10 and 20 days old for A+V+W and 3 days old for A+V+S) in comparison to the other treatments. G10 and G20 lambs of the A+V, A+V+W, and A+V+S groups also displayed greater values for walking activity (P < 0.05) in comparison with G3 lambs. In general, it is concluded that the exhibition of the examined behavioral parameters was increased with the degree of sensorial isolation, and particularly when the physical contact between the lambs and their dams was restricted. As lambs became older, they showed an increased behavioral reactivity in response to the increased sensorial isolation.