Special care of baby lambs, and sheep with young ones. When lambing time comes, the shepherd must take great care of his flock. The task is made more difficult because it so often becomes necessary to move to a new location to find pasturage. The sheep that are soon to become mothers, as well as those with their young ones, must be kept close to the shepherd while in transit. Little helpless lambs that cannot keep up with the rest of the flock, are carried in the bosom of his undergarment, the girdle turning it into a pocket.
Isaiah pictures this activity in his famous passage: "He shall feed his flock like a shepherd: he shall gather the lambs with his arm and carry them in his bosom, and shall gently lead those that are with young" (Isaiah 40:11).
[Manners And Customs of Bible Lands]