Pigs

A pig is kept first for meat and grows fast: started at about 23 kg (50 lb) it reaches a market weight of 113 to 127 kg (250 to 280 lb) in roughly six months. It also roots, working its snout through the ground and turning the soil over rather than scratching the surface as a bird does, so it can break open a bed before planting and feed itself as it goes.

The same habit is why a pig is hard to keep in the wrong place. It strips ground cover, digs roots free and gnaws bark from trees, so where it is confined and for how long decide whether the digging helps or harms. Fencing has to stop an animal going under rather than over, usually a single electric wire at ground level inside the pen. A three-sided shelter is enough on pasture. Water must be constant, from a fixed or portable drinker rather than a bucket, which pigs tip. Above about 21 degrees C (70 F) an animal over 68 kg (150 lb) needs cooling, and the options differ in water cost: a wallow, a shallow mud hole it lies in, takes about 5 litres (1.3 gal) a day per animal, a timed sprinkler 2 and continuous spraying 20.

Moving the animals to fresh ground about weekly is what makes the rest work; ground stocked continuously compacts and goes bare, and keeping about three quarters of it vegetated is the usual guide. Rotation also breaks the cycle of a roundworm whose eggs stay infective in soil for years and die only in composting that reaches roughly 63 degrees C (145 F). Pig ground and vegetable ground therefore cannot be the same without a long gap, and pig manure does not belong on beds where produce is handled by hand. It pairs best with an orchard or nut planting grazed in rotation, where the fallen crop is the point, and with a bed rotation that admits the animal between crops rather than onto growing ground. An escape is not a lost animal but the start of a feral population.