If you compare the natural lifespan of sheep in nature with their lifespan in intensive farming, the picture is very sad 

Sheep are the domesticated form of the mouflon. They were domesticated probably 10,000 years ago, and people have been using sheep meat and wool for over 5,000 years. Mouflons live around 16 years in captivity and around 8 to 12 years in the wild – where there are all kinds of dangers. The natural life expectancy of a domestic sheep is – if it is not slaughtered – 10 and up to 20 years. The oldest age recorded for a sheep was 28 years and she lived in Wales.

Today, many sheep that are used for production of mutton, roast lamb, dairy or wool products, live in intensive animal husbandry. Very few of them achieve their natural lifespan in this type of housing. In intensive farming, a wool sheep can live to be around seven years old - which means it has the longest life expectancy among its fellow species.

At three to four months old, lambs have a particularly short life before they end up on the plate as a roast lamb. Dairy sheep, breeding sheep and wool sheep live longer in comparison to lambs. However, their life expectancy in intensive animal husbandry is still more than ten years below the possible lifespan of the animals as they are killed after only a few years, when their production decreases.