Pig Production & Welfare
The most common breeds of pigs used are the British Landrace and Large white. The majority of pigs reared for meat in the UK are crossbreeds. For example, when a Landrace/Large White is bred with either a purebred Landrace or Large White this results in an increased number of stronger faster-growing piglets. Duroc crosses are used extensively in outdoor pig breeding units producing offspring more capable of coping with UK weather conditions in the winter and summer months(3). Sows are first mated when they are 6-8 months old. Around 80-90% of sows in the UK are serviced by artificial insemination (AI). Pregnancy lasts approximately 4 months and a sow will give birth (farrow) to 5-25 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 3-5 years for sausages, pork pies and other low-quality products. The natural lifespan of a pig is 10-15 years. Sows spend at least 2/3 of their lives in pregnancy, there are 500,000 breeding sows in the UK.
The majority of these are kept indoors. Until recently, sows were confined in Sow Stalls. These are barred stalls barely larger than the sow so she is unable to turn around. Sow Stalls are still commonly used outside the UK. They have concrete or slatted floors with no bedding. Intensive farming systems mean that pigs cannot display their natural tendencies and instead show unnatural behaviour such as tail biting, bar biting and head shaking.
Government legislation passed in October 1991 led to the banning of all stalls and tethers in the UK from January 1999 and the use of tethers in Europe was banned in 2005. The UK imported 800,000 tons of pork from countries such as the Netherlands and Denmark in 2004. An EU-wide ban on sow stalls came into force on 1 January 2013(1). Alternatives to stalls include keeping the sows indoors in groups where they are kept in enclosures and may have bedding. Increasing numbers of sows are being kept outdoors in less intensive systems due to welfare legislation. The Welfare of Farmed Animals (England) Regulations 2003 states that a pig should be able to turn around, stand up, lie down and rest without difficulty. However, this does not apply when the sow is moved to a farrowing crate(1).
A week before intensively kept sows give birth they are moved into farrowing crates, these metal crates are barely larger than the sow. The sow’s movement is severely restricted, she is unable to turn around or suckle her piglets. Any attempt at movement means the sow will unavoidably rub herself against the crate bars causing sores, abrasions and swellings. Sows will remain in these crates for 3-4 weeks until the piglets are weaned.
The strong instinct to build a nest (out of natural materials such as grass or straw) leaves the sows completely frustrated. Close confinement can cause muscle weakness, lameness and inflammatory swellings of the joints. Farrowing crates are used as 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 un-crated systems. Alternatives to the standard farrowing crate have been studied.
The Ellipsoid Farrowing Crates allow the sow to turn around and give them more freedom to move. Studies have shown that sows turn approximately 40 times a day and the increase in movement did not cause a higher pig crushing rate than the standard farrowing crate. Behavioural observations showed that the Ellipsoid Farrowing crate permitted easier visual and tactile contact of sows with their young and also offered piglets better access to the sow’s teats(4).
The Werribee Farrowing Pen has a sow and piglet (nest) area and non nest area. This provides twice the space of a standard farrowing crate(5). Attempts to reduce crate size lead to a sharp increase in piglet pre-weaning mortality. One study comparing behaviour and performance of lactating sows and piglets reared indoors and outdoors have shown that piglets spend more time walking and playing when housed outdoors(6). Studies comparing the behaviour of sows housed indoors (farrowing crates) and outdoors in paddocks have shown that if the environment allows then pigs will spend hours making a nest to give birth to their young in(7).
In comparison, confined sows with no access to material to build a nest spent a large part of their last hours prior to giving birth pawing, rooting, nosing and biting parts of the crate. Depriving sows of space and material to perform natural nesting has shown negative effects on behaviour. This includes abnormal behaviour and psychological stress, reduced piglet survival and the savaging of piglets. The Department for Environment Food and Rural Affairs (DEFRA) are funding research to develop and test commercially viable farrowing systems that do not closely confine the sow, but provide adequate protection to piglets. After weaning, the majority of young pigs are reared in groups in small pens (batch pens) or metal cages. Those with slatted or perforated floors without bedding often cause injury to legs and feet. Under the Welfare of Farmed Animals Regulations (2003) the amount of unobstructed floor area available to each pig ranges from 0.15m2 (10kg pig) to 1.00m2 (pigs over 110kg) (1). Pens are typically overcrowded, poorly lit and without bedding.
Pigs can become bored and aggressive with tail-biting and excessive fighting occurring. Piglets therefore often have their teeth clipped and tails docked. Piglets are generally not castrated in the UK as they are slaughtered before sexual maturity. These procedures may be performed in the first few days after birth without a vet being present. The Welfare of Farmed Animals Regulations (2003) states that if the piglet is older than one week then these aforementioned procedures should be carried out under anaesthetic by a veterinary surgeon. 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).
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