Abstract: It is known that the right and left brain hemispheres differ in their ability to regulate autonomic processes in the organism. Direct unilateral stimulation of the brain provokes side-dependent endocrine, immune and other visceral reactions. Since brain hemispheres are mainly involved in the regulation of muscles and sensory organs on the contra lateral side of the body the activation of behavioural asymmetry stimulates the contra lateral half of the brain. The important theoretical and practical question of whether autonomic processes can be regulated via the behavioural asymmetry route remains unexplored. In this study, we report that the chronic presentation of an emotionally important stimulus--food--from the left side, improves reproductive performance in animals in a broad range of feeding conditions. The unilateral presentation of food can also influence lactation, but in this case the side-dependent effects are different under varying feeding conditions. This finding opens a simple practical approach to influence basic somatic functions in the organism.

Abstract: This study investigates behavioural lateralization in sheep and lambs of different ages. A flock was tested in a task in which the animals were facing an obstacle and should avoid it on either the right or left side to rejoin flock-mates (adult sheep) or their mothers (lambs). A bias for avoiding the obstacle on the right side was observed, with lambs apparently being more lateralized than sheep. This right bias was tentatively associated with the left-hemifield laterality in familiar faces recognition which has been documented in this species. Differences between adult sheep and lambs were likely to be due to differences in social reinstatement motivation elicited by different stimuli (flock-mates or mothers) at different ages. Preferential use of the forelegs to step on a wood-board and direction of jaw movement during rumination was also tested in adult animals. No population bias nor individual-level lateralization was observed for use of the forelegs. At the same time, however, there was a large number of animals showing individual-level lateralization for the direction of jaw movement during rumination even though there was no population bias. These findings highlight that within the same species individual- and population-level lateralization can be observed in different tasks. Moreover, the results fit the general hypothesis that population-level asymmetries are more likely to occur in tasks that require social coordination among behaviourally asymmetric individuals.