PIGS, WILTSHIRE: David farms 94 acres (38 hectares), all grass, on the edge of Salisbury Plain. He has farmed here since 1987 and was originally a dairy farmer, milking 80 cows. He now keeps 400 sows, producing 9,000 finished pigs every year.

The sows farrow (give birth) outdoors and spend their pregnancy (gestation) indoors in straw yards. The weaners (four week old piglets), and growers (10 to 17 weeks old) are housed in converted dairy buildings on deep straw. About five to seven weeks before they are ready for slaughter, at 22 to 24 weeks of age, they are moved into fully slatted modern pig buildings with automatically controlled natural ventilation.

Outside, the farrowing sows and gilts (young females that have not yet produced piglets) are rotated around the farm every two years, occupying 30 acres at any one time. The rest of the land is grazed by a neighbour’s sheep.

David’s pigs are sold through a major processor and end up on the supermarket shelves.