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What are the animal welfare issues with pig farming?

In Australia, pigs farmed for meat are housed in several types of farming systems including intensive indoor systems, semi-indoor (outdoor bred) systems and outdoor (free-range) systems [1].

The use of intensive indoor housing systems for pigs leads to several serious welfare problems. Indoor systems have arisen for a number of reasons, including climate control, ease of cleaning, use of labour-saving equipment and protection from predators. However, these systems result in barren environments with no enrichment, sow and boar confinement, restricted sow feeding and routine painful husbandry procedures (ear notching, teeth clipping and tail docking).

Barren environments and lack of enrichment

Barren environments, such as those in intensive systems, provide minimal opportunities for pigs to explore and forage – behaviours they are highly motivated to perform – leading to boredom and frustration. This can lead to aggressive behaviour being directed towards other pigs, such as nosing and biting, or the development of stereotypies. Stereotypies are abnormal repetitive behaviours that can occur in response to stress, such as repeated licking, bar-biting or sham chewing [2]. Pigs in barren environments have also been shown to have higher salivary cortisol (stress hormone) levels than pigs in more enriched environments, indicating that they may be chronically stressed [3].

Sow stalls and farrowing crates

Both sow stalls and farrowing crates involve the confinement of pigs in metal-barred crates, in which sows (female pigs) are only able to stand and lie down but are unable to turn or walk around. When confined, pigs are unable to socialise or perform highly motivated behaviours, for example exploratory or nesting behaviour in pregnant sows. As a result, sows can become stressed and frustrated leading to the development of stereotypies and aggression. Sows, when confined, can also suffer from reduced bone strength, impaired mobility and reduced cardiovascular fitness. Confinement during farrowing (birthing) has also been shown to be associated with an increased number of stillbirths and aggressive behaviour towards piglets [4]. To learn more about the welfare issues with sow stalls and farrowing crates click here.

The Australian pig industry has committed to voluntarily phasing out sow stalls. The majority of sows are now housed in groups except for the 5 days after mating where they are confined to mating stalls, and the 7 days before farrowing where they are placed in farrowing crates until their piglets are weaned. Where sow stalls are still in place, regulation currently requires that they cannot be used for more than 6 weeks during gestation (pregnancy) [1, 5].

Boar stalls

A boar stall is like a sow stall but for boars (adult male pigs). It is a metal-barred crate slightly larger than a sow stall at just 2.4m long and 70cm wide. Like sow stalls, boar stalls only allow enough room for the boar to stand and lie down but he is unable to turn or walk around. Boars are only taken out of these stalls for mating (semen collection) or an occasional short walk during the week. Boars in these stalls suffer the same negative welfare effects as confined sows including stress, frustration, development of stereotypies and impaired mobility. Unfortunately, the Australian pig industry has made no commitment yet to phase out the use of boar stalls in pig farming.

Restricted feeding of sows

The feed intake of breeding sows is commonly restricted to improve productivity (e.g. pregnancy rate) and manage mobility issues of confined sows. Sows are naturally motivated to spend a large amount of time during the day foraging and eating. In intensive farming systems, feed is provided in the form of a pelleted ration which is eaten very quickly, and sows are housed in barren environments with minimal enrichment. This means the time sows would normally spend performing motivated behaviours like foraging and eating is greatly reduced resulting in sows experiencing hunger and frustration, which can lead to increased aggression, feeding competition between sows, and the development of oral stereotypies (licking, bar-biting, sham-chewing or vacuum-chewing) [2, 6].

Piglet husbandry procedures

In the first few days of life, piglets may undergo several painful husbandry procedures such as ear notching, teeth clipping and tail docking. These painful procedures are routinely performed on piglets without anaesthesia or pain relief. Following these procedures, piglets show obvious signs of pain and distress such as squealing, chomping, clamping their tails between their hind legs, tail wagging and head shaking [7]. To read more about the welfare issues with piglet husbandry procedures click here.

Male piglets may also be castrated to reduce the risk of aggressive behaviour and undesirable meat characteristics (boar taint). Physical castration is usually performed without anaesthesia or pain relief, resulting in significant pain and distress for the piglet. Alternative methods such as immunological castration currently provide a more humane option than physical castration. If piglets are not castrated, they are usually sent to slaughter before they reach sexual maturity.

Weaning

Weaning refers to the removal of milk from the suckling piglets’ diet by gradually or abruptly removing piglets from the sow when piglets are 3 to 4 weeks of age. Natural weaning of piglets would normally occur gradually over a period of up to 5 months.

For piglets, weaning is very stressful due to being separated from their mother and mixing with unfamiliar piglets in a new environment. Due to the change in diet and piglets’ immature gastrointestinal tract, low feed intake following weaning can result in poor intestinal function, diarrhoea and reduced growth rate. Piglets that are weaned early (before 28 days of age) are more likely to develop abnormal behaviours such as belly nosing, navel sucking, chewing body parts of other piglets and increased levels of aggression.

What is RSPCA’s position?

RSPCA Australia believes that in all farming systems, animals must be provided with freedom of movement and the ability to satisfy their behavioural, social, and physiological preferences and needs. Pregnant sows must be able to exhibit nesting behaviour and all pigs must be able to root, forage and explore. Under the RSPCA Approved Farming Scheme Standard – Pigs, pigs must have bedding and enrichment, and sow stalls, farrowing crates and aversive piglet husbandry procedures are not permitted. Visit the RSPCA Approved Farming Scheme website for more information.

References

[1] Australian Pork: Our Farming Systems (2020).

[2] Hemsworth P (2018) Key determinants of pig welfare: implications of animal management and housing design on livestock welfare. Animal Production Science, 58:1375-1386.

[3] Van de Weerd H (2009) A review of environmental enrichment for pigs housed in intensive housing systems. Applied Animal Behaviour, 116:1-20.

[4] Pedersen LJ (2018) Advances in pig welfare – overview of commercial pig production systems and their main welfare challenges. Herd and Flock Welfare, Ch1 pp3-25.

[5] Primary Industries Standing Committee (2008) Model Code of Practice for the Welfare of Animals: Pigs 3rd Edition. PISC Report 92.

[6] Meunier-Salaün M, Edwards S, Robert S (2001) Effect of dietary fibre on the behaviour and health of the restricted sow. Animal Feed Science and Technology, 90:53-69.

[7] AVMA (2014) Literature review on the welfare implications of teeth clipping, tail docking and permanent identification of piglets.

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Updated on August 12, 2020
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https://kb.rspca.org.au/knowledge-base/what-are-the-animal-welfare-issues-with-pig-farming/

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