Dietary Habits and Social Interactions Affect Choice of Feeding Location by Sheep,
Applied Animal Behavior Science
Individuals often occur in subgroups that differ in their choice of forage and habitat, even within the same environment. Different foods occur in disparate locations and thus differences in dietary habits could provide one explanation for the formation of subgroups and their use of the environment. In addition, subgroups may form as a result of social interactions. We conducted experiments to study the effects of food preference and social interactions on choice of feeding location by lambs. In 1992, 12 lambs that had been reared together were separated into two groups of six lambs. Groups were conditioned to prefer one of two grains, either milo (Sorghum bicolor) or wheat (Triticum aestivum) by feeding milo or wheat for 14 days. Lambs were conditioned to avoid the other grain by following its ingestion with a mild dose of the toxin lithium chloride (LiCl) on 3 consecutive days. During testing, milo and wheat were placed at opposite ends of a 0.25 ha pasture. Lambs were first allowed to feed as groups consisting of three lambs that preferred milo and three lambs that preferred wheat, and then allowed to feed as groups in which one lamb preferred milo with three lambs that preferred wheat, and vice versa. Under both conditions, lambs always foraged on their preferred food, even when the locations of the foods were switched. In 1993, we repeated the study from 1992 in a larger pasture (1 ha) and without the use of LiCl. Lambs were reared in three different groups and fed either milo (Group 1), wheat (Group 2), or half of the lambs were fed milo and the other half were fed wheat (Group 3) for 4 months to condition a preference for either milo or wheat. When we combined lambs that preferred milo from Group 1 with lambs that preferred wheat from Group 2 to form subgroups of strangers, lambs fed in different locations. Conversely, social interactions and food preferences both affected choice of foraging location when lambs were reared together (companions). For instance, some lambs that preferred wheat grazed in the vicinity while peers ate milo, whereas lambs that preferred milo grazed in the vicinity while peers ate wheat. In other cases, one or two lambs separated from the rest of the group and ate their preferred grain. We conclude that food preference had a primary influence on choice of foraging location when lambs were reared separately (strangers) and preferred different foods. Food preferences and social interactions both influenced choice of foraging location for companions unless animals were made averse to one of the foods with LiCl, in which case dietary preferences overrode social influences.
Scott, C. B., Provenza, Frederick D.; Balph, David F. 1988. Dietary Habits and Social Interactions Affect Choice of Feeding Location by Sheep. Journal of Animal Science 45: 225-237.