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What are the animal welfare issues associated with pig production?

In Australia, pigs farmed for meat may be housed in intensive indoor, semi-indoor (outdoor-bred) or outdoor (free-range) farming systems. Intensive indoor housing systems can lead to several serious welfare problems. These systems can result in barren environments without enrichment, in which sow and boar movement is confined, sow feeding is restricted, and piglets undergo 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 perform highly motivated behaviours (e.g., exploring and foraging) which can lead to boredom and frustration. This in turn can lead to aggressive behaviour being directed towards other pigs, such as nosing and biting, or the development of abnormal behaviours, such as stereotypies. Stereotypies such as repeated licking, bar biting or sham chewing, are abnormal repetitive behaviours which can occur when pigs are attempting to cope in response to stress or an inappropriate environment [1]. 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 [2].

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) can stand and lie down but are unable to turn or walk around. A standard sow stall is just 2m long and 60cm wide and a farrowing crate is slightly narrower. When sows are unable to move freely, it can result in reduced bone strength, impaired mobility and reduced cardiovascular fitness. In addition, sows are unable to socialise or perform highly motivated behaviours, for example exploratory or nesting behaviour in pregnant sows. As a result, sows can become chronically stressed and frustrated leading to the development of stereotypies and aggression.

During gestation (pregnancy) and farrowing (birthing), chronic stress and confinement has been shown to be associated with an increased number of stillbirths and negative consequences for piglet foetal development, which can have long-lasting negative effects on the piglet’s health and welfare [3]. When confined, sows are also unable to perform natural nursing and maternal behaviours and may show aggressive behaviours towards their piglets [4, 5]. To learn more about the welfare issues with sow stalls and farrowing crates, click here.

The Australian pig industry committed to voluntarily phasing out sow stalls by 2017. The majority of sows are now housed in groups except for the five days after mating where they are confined to mating stalls, and the seven days before farrowing where they are confined 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 six weeks during gestation (pregnancy) [6].

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 chronic stress, frustration, development of abnormal behaviours (e.g., 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 will naturally spend a large amount of their time during the day foraging and eating when provided the opportunity. In intensive farming systems, feed is provided in the form of a pelleted ration which is usually eaten very quickly, and sows are housed in barren environments with minimal to no enrichment. This means the time sows would normally spend performing motivated behaviours like foraging and eating is greatly reduced, increasing the likelihood that sows experiencing negative welfare outcomes, such as chronic hunger and frustration. In the long term, this can lead to increased aggression and feeding competition between sows, as well as the development of oral stereotypies (licking, bar-biting, sham-chewing or vacuum-chewing) [1, 7].

Painful piglet husbandry procedures

In the first few days of life, piglets may undergo several painful husbandry procedures such as ear tagging or notching, teeth clipping and tail docking. These painful procedures require piglets to be handled and restrained and are routinely performed all at the same time without anaesthesia or pain relief. Following these procedures, piglets show obvious signs of pain and distress such as vocalising (i.e., squealing), trembling, chomping, clamping their tails between their hind legs, tail wagging and head shaking [8, 9]. In Australia, pigs are required to be identified for traceability purposes making ear tagging mandatory. Teeth clipping and tail docking are not required and instead are routinely performed to prevent negative piglet behaviours such as tail biting and aggression, which could be addressed through alternative husbandry and management strategies [9, 10]. 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 (i.e., 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.

Early 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 three to four weeks of age. Natural weaning of piglets would normally occur gradually over a period of up to five 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 and diarrhoea, reduced immune system function and decreased productivity [11, 12]. Piglets weaned early (before 28 days of age) are also 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 the 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. The RSPCA opposes high-confinement systems, including the use of sow stalls, farrowing crates, boar stalls, and mating stalls. Pigs must be provided with adequate space throughout their lifetime and be able to root, forage and explore, while pregnant sows must be able to exhibit nesting behaviour.

The RSPCA Approved Farming Scheme Standard – Pigs does not permit confinement in sow stalls, farrowing crates, and mating stalls, or painful husbandry procedures for piglets. Under the RSPCA Approved Farming Scheme, pigs must be housed in enriched indoor and/or outdoor systems with more space to move, forage, socialise and explore than regulations require. Visit the RSPCA Approved Farming Scheme website for more information.

References

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

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

[3] Lagoda ME, Marchewka J, O’Driscoll K and Boyle LA (2022) Risk factors for chronic stress in sows housed in groups, and associated risks of prenatal stress in their offspring. Frontiers in Veterinary Science 9, 883154.

[4] Wiechers D-H, Herbrandt S, Kemper N et al. (2022) Does nursing behaviour of sows in loose-housing pens differ from that of sows in farrowing pens with crates? Animals 12, 137.

[5] 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.

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

[7] 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.

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

[9] Schmid SM, Steinhoff-Wagner J (2022) Impact of routine management procedures on the welfare of suckling piglets. Veterinary Sciences 9(1), 32.

[10] Hemsworth L, Hemsworth P, Acharya R et al. (2018) Review of the scientific literature and the international pig welfare codes and standards to underpin the future Standards and Guidelines for Pigs. Final Report APL Project 2017/2217.

[11] Campbell JM, Crenshaw JD, Polo J (2013) The biological stress of early weaned piglets. Journal of Animal Science and Biotechnology 4, 19.

[12] Ming D, Wang W, Huang C, Wang Z, Shi C, Ding J, Liu H, Wang F (2021) Effect of weaning age at 21 and 28 days on growth performance, intestinal morphology and redox status in piglets. Animals 11(8), 2169.

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Updated on July 6, 2022
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https://kb.rspca.org.au/knowledge-base/what-are-the-animal-welfare-issues-associated-with-pig-production/

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