Management systems for intensive commercial pig production
There is no standard or system of housing for pigs. Instead, accommodation and equipment are chosen to suit the type of management system for commercial pig production. However, there are certain similar principles and practices in most systems. These originate from the fact that most pig units will contain pigs of different classes.
Farrowing – suckling pens
In small and medium scale intensive pig production units a combined farrowing, suckling and rearing pen is normally used. The sow is brought to this pen one week before farrowing and stays there together with her litter for 5 to 8 weeks when the piglets are weaned by removing the sow. The sow is often confined in a farrowing crate a few days before, and up to a week after birth to reduce piglet mortality caused by overlaying or trampling.
Early weaning after a suckling period of 5 to 6 weeks or even less can only be recommended where management and housing is of good standard.
The piglets remain in the farrowing pen after weaning and until they are 12 to 14 weeks of age or weigh 25 to 30 kg.
Group keeping of farrowing-suckling sows that have given birth within a 2 to 3 weeks interval is possible, but is unusual in intensive production. However, there a few acceptance problems and the litter cross-suckle and mix freely. The pen should have at least 6m2 deep litter bedding per sow, with an additional creep area of 1m2
In a large scale unit, which has separate farrowing house, sometimes either of the following two alternative systems is practiced instead of the system described above.
The first alternative is similar to the system described above but the piglets are moved two weeks after weaning to a weaner pen where they remain either until they are 12 to 14 weeks of age (25 to 30kg) or until 18 to 20 weeks (45 to 60kg). Note that the piglet should always remain in the farrowing / suckling pen for a further 1 to 2 weeks after the sow has been removed so that they are not subjected to any new environmental or disease stress at the same time as they are weaned. The weaning pens can contain one litter or up to 30 to 40 pigs. The pigs are often fed ad libitum.
In the second alternative the sow is placed in a farrowing crate in a small pen one week prior to birth. Two weeks after farrowing the sow and litter are moved to a larger suckling pen until 12 to 14 weeks of age or be transferred to weaner accommodation two weeks after weaning.
Dry sow pens
After weaning a sow will normally come to heat within 5 to 7 days and then at 3 weeks interval until successful mating. The average weaning to conception interval can vary between 8 – 20 days depending on management. In the period until pregnancy has been ascertained the sow is best kept in a pen or stall in close proximity to the boar pen.
Gestating sows are kept in yards or pens in groups of up to 10 to 12 sows that will farrow within 2 to 3 weeks interval. They can also be kept in individual pens confined in stalls or tethered in stalls.
Weaner and fattening pens
The weaners, whether they come from a farrowing pen or a weaner pen, will at 12 to 14 weeks of age be sufficiently hardened to go to a growing / finishing pen. Finishing can be accomplished either in one stage in a growing / finishing pen from 25 to 90kg or in two stages so that the pigs are kept in a small growing pen until they weigh 50 to 60kg and are then moved to a larger finishing pen where they remain until they reach marketable weight.
Although finishing pens are sometimes kept in groups of 30 or more, pigs in a group of 9 to 12, or even less, show better growth performance in intensive systems. An alternative, where growing and finishing are carried out in the same facility, is to start about 12 pigs in the pen and later, during the finishing period, reduce the number to 9 by taking out the biggest or smallest pigs from each pen.
In intensive systems a sow will, on average, produce 3 to 6 litters before she is culled of infertility, low productivity or age. Yung breeding stock should be separated from the rest of the litter at about 3 months of age, since they should be less intensively fed than the fattening pigs. Gilts are first covered when they are 7 to 9 months of age or weigh 105 to 120kg. After mating they can either be kept in the same pen up to 1 week before farrowing, or kept in the gestating sow accommodation, but in a separate group.
Boars are usually quiet if run with other boars or with pregnant sows, but may develop vicious habits if shut up alone.