To many, pasture lambing is a novel idea, however, unassisted, unsupervised lambing is the method used by the majority of sheep operations in the western United States. Many farm flock operations are moving towards pasture lambing because of lower production costs and reduced labor. Additionally, environmental conditions are generally more suitable for newborn lamb survival in May than January through March. Additionally, depressed lamb prices in recent years have also forced producers to consider pasture lambing to reduce costs.
Morrical, Daniel G., "The Ins and Outs of Pasture Lambing" (2003). Animal Science White Papers, Technical Reports, & Fact Sheets. 3.