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Information Sheet
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Pigs There are around 7-8 million pigs in the UK, reared primarily for bacon, ham, pork and sausages. The majority of pigs in the UK are reared under very intensive conditions, being closely confined for most of their lives. Pigs are naturally intelligent and inquisitive social animals. Originally pigs lived in woodlands, foraging for nuts, seeds, roots and grubs. They will not soil their resting area and the myth that pigs are somehow dirty comes from their wallowing in wet mud. They do this to cool down in hot weather and to rid themselves of pests. PIG PRODUCTION Sows are first mated when they are 6-8 months old. Around 80-90% of sows in the UK are serviced by artificial insemination. Pregnancy lasts 16.5 weeks and a sow will give birth to (farrow) between five and 25 piglets in a litter (averaging 10-12). Piglets are prematurely weaned after 2-4 weeks (weaning would naturally occur at 12-14 weeks) and a week later the sow will be serviced again. The average number of pigs reared per sow is 22 each year though many sows rear more than this. Sows produce around 4-7 litters before they become exhausted and are slaughtered after 3-4 years for sausages, pork pies and other low-quality products. The natural lifespan of a pig is 10-15 years. Sows spend at least two-thirds of their lives in pregnancy. There are 800 000 breeding sows in the UK. About 50% of these are kept indoors, until recently in Sow Stalls - barred stalls so narrow the sow is unable to turn around which are still commonly used outside the UK, or tethers. In tether stalls the sow is tethered by a heavy chain attached to a strap around the pigs neck or body. Floors are concrete or slatted and do not have any bedding. When first tethered sows can become very distressed and struggle frantically. Lameness, other leg, back and hip problems and sores are all common. Sows also show stereotypic behaviour such as gnawing and biting stall bars. Government legislation passed in October 1991 led to the banning of all stalls and tethers from January 1, 1999. However much pigmeat is imported from other European countries. EC legislation means tethers are to be banned in all EC countries from 2005 but no action has been taken on sow stalls. Alternatives to stalls and tethers include keeping the sows indoors in groups. Sows are kept in enclosures and may have bedding. Increasing numbers of sows are being kept outdoors in less intensive systems. Increasing numbers of sows are now housed outdoors and this is increasing due to the welfare legislation. A week before giving birth sows are moved to farrowing crates where they stay for 2-4 weeks until the piglets are weaned. Farrowing crates are metal crates barely larger than the sow, giving no room for turning around. Any attempt at movement means the sow will unavoidably rub herself against the crate bars causing sores, abrasions and swellings. The strong instinct to build a nest out of leaves, grass or straw is completely frustrated. Over 80% of mothering sows are kept in farrowing crates. Farrowing crates are used because otherwise it is claimed that piglets would be crushed by the sow lying on them. However, sows in farrowing crates are prevented from manoeuvring and lying down carefully so piglets are in danger of being crushed by the sow clumsily dropping down. Studies have found piglet mortality is no different between crated and uncrated systems. Intensification has lead to increased disease problems, particularly prevalent amongst piglets. Viral pneumonia, meningitis, swine vesicular disease, blue-ear disease and scours are a few of the many diseases that can affect pigs. In order to prevent this specific pathogen free (SPF) methods have been developed to rear piglets in a sterile environment. One once popular scheme involves killing the sow shortly before birth and removing the piglets still within the womb. The entire womb is transferred to a sterile room and the piglets are cut free and reared. SPF is used on a small proportion of the breeding herd. After weaning the young pigs are reared in groups in small pens or metal cages. Slatted or perforated floors without bedding often cause injury to legs and feet. Pens are typically barren, overcrowded and poorly lit. Pigs can become bored and aggressive and tail-biting and excessive fighting may occur. Because of this piglets often have their incisor teeth and tails clipped. Teeth are cut almost down to gum level without anaesthetic. Similarly, tail-docking doesn't require an anaesthetic. Both these operations may be performed in the first few days after birth without a vet being present. Some male piglets are also castrated without anaesthetic. This is to avoid boar taint, a strong flavour in meat from sexually mature male pigs. However, pigs are generally slaughtered before reaching sexual maturity and less than 5% of male pigs are estimated to produce meat with an unacceptable taint. After about six weeks, the pigs are transferred to the fattening house. These are usually indoor enclosures with slatted or concrete floors and no bedding. A few pigs are selected for breeding stock. The rest are sent for slaughter. SLAUGHTER Pigs are usually slaughtered after 4-7 months. Pigs intended for pork are usually slaughtered 1-2 months younger than pigs for bacon. Around 15 million pigs are slaughtered each year. Slaughter of pigs involves stunning followed by throat-slitting (called sticking). Pigs are usually stunned electrically by placing tongs on either side of the neck behind the ears. It is believed a high proportion of pigs are not adequately stunned, due to the tongs not being held in place for long enough or being incorrectly placed. Also, many abattoirs may routinely use an inadequate voltage. Because of this many pigs regain consciousness during bleeding out or even before throat-slitting. Some pigs are stunned using carbon dioxide gas. This is less common in the UK but widely used in other countries such as Denmark. Carbon dioxide stunning has been strongly criticised by scientists as inhumane, pigs suffering from breathlessness and hyperventilation whilst trying to escape. BREEDING Pig breeding is a major industry, breeds being selected for rapid growth, high lean meat content and other economically desirable traits. The UK leads the world pig breeding industry with companies such as the Pig Improvement Company (PIC) and the National Pig Development Company (NPD). Modern pigs have been selectively bred for fast growth which can lead to lameness and other leg problems, the pigs being unable to support their own rapid weight gain. Around 15% of pigs are estimated as suffering from lameness though this may be considerably higher in some herds. Mothering pigs have the added problem of coping with rapidly growing suckling piglets. This can cause the sow a loss of bodyweight and loss of bone tissue leading to hip or spinal bone fractures. Pig breeders have now developed a new sow with extra teats and larger litters. This has involved crossing a traditional British breed with the Chinese Meishan pig. Meishan sows have up to 18 teats and average 16 piglets/litter compared with 12 teats and 11 piglets for British breeds. They are very high in fat though so not suited to the meat industry's requirements. Cross breeding has produced a hybrid, called the Manor Meishan, with the advantages of the Meishan but with a lean meat content. The pig industry hopes this new breed will produce 30-40 piglets/year. Other breeding has involved developing breeds that are less prone to stress. Porcine stress syndrome (PSS) is attributed to a specific gene, called the halothane gene. PSS leads to pale, watery meat of low quality, poor appearance and shortened shelf life. Selective breeding has produced strains in which the halothane gene has been eliminated. These stress-free pigs have lower mortality (especially during transport to slaughter when many deaths can occur) and are said to produce higher quality meat. Genetic engineering techniques are likely to become important for producing even more profitable pigs in the future. An Australian company have developed a pig incorporating a small segment of human genetic material. The pigs produce extra growth hormone so grow faster on less feed and produce very lean meat. Previous attempts to produce transgenic pigs in the US yielded pigs that were impotent, arthritic and barely able to stand. Further Information
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