Commercial pigs farms buy in gilts (unmated females) and once they are old enough these are inseminated; either naturally by a boar or artificially using a catheter and diluted bought in semen.
The females are housed in gestation (dry sow) houses for their pregnancy. They are fed a balanced diet to ensure the growing foetuses are well nourished and that the sow puts on sufficient fat reserves for lactation.
Approximately 5 days before due date females are taken to a farrowing house which is specially designed to keep the newborn piglets with their mothers. The essence of the house is to provide warmth and protection for the piglets and at the same time a cool climate for the mother, an often very difficult task.
The piglets suckle on the mother for 4 weeks in which time they grow from a birth mass of 1,3 kg to a weaning weight of 7,5 -8 kg.
Most sows (females that have produced a litter) will spend 3 years on a farm and produce 6 to 8 litters. As a sow gets older the litter size declines as well as milk production.
The newly weaned piglets (weaners) are grouped together in groups ranging from 15-300 in purpose built houses that provide warmth, fresh air, and ready access to food and water. Commercial farmers know this is a critical time in the young pig’s life and so they take special care of the dietary needs of these animals. (see later).
Weaners will spend 5,5 to 6,5 weeks in the weaner houses before being transferred to the next stage /building /site. At this time these pigs will be weighing anything from 28,5 to 35 kg.
The grower buildings are designed with appropriate pace for the larger pigs being grown out to market weight. Depending on the layout and drainage system 0,85 to 1,1 m2 should be provided. Pigs used by processors , known as baconers, will be approximately 100 kg in weight at 21-22 weeks of age; while, porkers will be 3-4 weeks younger and approximately 20 -25 kg lighter.
Source: CS Vet – www.csvet.co.za