Shepards used their old sheep as a food source
Life in the countryside is pretty difficult, and in the eighteenth century, it must have been harder. Animals were needed in many ways by farmers and their families. Sheep, for example, were incredibly valuable because their wool was useful to knit clothes as well as covers. But people also used their meat when they got old.
Sadly, once the sheep have reached a certain age (commonly a year or so), their wool loses a lot of its quality, so some families decided to kill the animal to use its meat. Old sheep meat is called mutton, and it remains a popular countryside meal even today.