The welfare of pigs is directly influenced by their environment. In farm animal husbandry, the living conditions of the animals are determined by humans and are adapted to the goals of farming. The breeding, keeping, and handling of animals has far-reaching effects on all areas of their existence.
To better illustrate this, the animal welfare specialist Fraser (1) divides three dimensions of animal welfare: health, behavior, and emotions. It should be noted that animal welfare is not a purely measurable concept. Some measurable parameters, such as the level of stress hormones, can be used to draw conclusions about well-being. Nevertheless, the assessment of quality of life, whether something is good or bad for an animal, depends on the values of the observing person. Animal rights activists evaluate situations differently than veterinarians in farms. According to Fraser, it is therefore important that the animal welfare research field does not attempt to set measurable values, but instead identifies, solves, and prevents factors that harm animal welfare (2).
The following highlights the three dimensions of the welfare of pigs under the living conditions of agricultural use.
(1) Fraser, D. (2008). Understanding animal welfare. Acta Veterinaria Scandinavica, 50(1), 1-7.
(2) Fraser, D. (1995). Science, values and animal welfare: exploring the ‘inextricable connection’. Animal welfare, 4(2), 103-117.
The poor housing conditions and high performance requirements for the pigs have health consequences for them.
Gastric ulcers, which are a consequence of food supply and composition, are typical in fattening (3). Standing and lying on hard ground and limited mobility lead to painful claw injuries and skin damage (4), (5). The harmful gas emissions in the pen lead to respiratory diseases (6).
Frequent births and large litters have negative effects on the genital tract and teats in sows (7), (8). The long-lasting and repeated fixation in the crates harms the locomotor system of the animals (9). Many sows suffer from shoulder injuries because they have to lie permanently on the hard ground (10).
(3) European Food Safety Authority (EFSA). (2007). Opinion of the Scientific Panel on Animal Health and Welfare on a request from the Commission related to animal health and welfare in fattening pigs in relation to housing and husbandry. EFSA Journal, 5(10), 564.
(4) Calderón Díaz, J. A., Fahey, A. G., & Boyle, L. A. (2014). Effects of gestation housing system and floor type during lactation on locomotory ability; body, limb, and claw lesions; and lying-down behavior of lactating sows. Journal of animal science, 92(4), 1675-1685.
(5) European Food Safety Authority (EFSA). (2007). Animal health and welfare aspects of different housing and husbandry systems for adult breeding boars, pregnant, farrowing sows and unweaned piglets‐Scientific Opinion of the Panel on Animal Health and Welfare. EFSA Journal, 5(10), 572.
(6) Bachmann, K., Köppler, J., Vergara, H., Frosch, W., & Zucker, B. A. (2008). Stallklima-Tiergesundheit-Wechselwirkungen zwischen Stallklima und Tiergesundheit. Schriftenreihe der Sächsischen Landesanstalt für Landwirtschaft, Heft 7/2007.
(7) Landesamt für Umwelt, Landwirtschaft und Geologie (LfULG). (2010). Auf dem Weg zur optimalen Abferkelbucht: Verletzungen am Gesäuge verringern!
(8) Milligan, B. N., Fraser, D., & Kramer, D. L. (2001). Birth weight variation in the domestic pig: effects on offspring survival, weight gain and suckling behaviour. Applied Animal Behaviour Science, 73(3), 179-191.
(9) Scientific Veterinary Committee (SVC). (1997). The welfare of intensively kept pigs. European Commission, Brussels.
(10) Ekesbo, I., & Gunnarsson, S. (2018). Farm animal behaviour: characteristics for assessment of health and welfare. CABI.
Pigs live under near-natural conditions in family groups of sows and their offspring. Boars spend their lives alone or in groups with other boars depending on the season and age. Struggles are rare in stable communities. The animal welfare specialists Ekesbo and Gunnersson (11) note that despite intensive husbandry and breeding, pigs show very individual behavior and react differently in different situations.
Social contacts are particularly important for pigs. Many of their behaviors show them synchronized, like joint resting and foraging, which takes about seven hours a day (12), (13). The rationing of food used in animal husbandry does not satisfy these needs under any circumstances. Since they cannot search for food themselves and their pens are almost completely unstructured, the curious animals lack activity and stimulation (14).
In forests and open fields where pigs normally live, they use different areas for excretion, lying and resting, and for active behavior. The small pens do not allow this separation (15), (16).
In addition to the complete restriction of movement of the sows in the crates, they cannot build a nest as they would under near-natural conditions (17). In addition, they have no unrestricted contact with their offspring (18).
(11) Ekesbo, I., & Gunnarsson, S. (2018). Farm animal behaviour: characteristics for assessment of health and welfare. CABI.
(12) Ekesbo, I., & Gunnarsson, S. (2018). Farm animal behaviour: characteristics for assessment of health and welfare. CABI.
(13) Richter, T. (2006). Krankheitsursache Haltung: Beurteilung von Nutztierställen-Ein tierärztlicher Leitfaden. Georg Thieme Verlag.
(14) European Food Safety Authority (EFSA). (2007). Animal health and welfare aspects of different housing and husbandry systems for adult breeding boars, pregnant, farrowing sows and unweaned piglets‐Scientific Opinion of the Panel on Animal Health and Welfare. EFSA Journal, 5(10), 572.
(15) Ekesbo, I., & Gunnarsson, S. (2018). Farm animal behaviour: characteristics for assessment of health and welfare. CABI.
(16) Fraser, D., Duncan, I. J., Edwards, S. A., Grandin, T., Gregory, N. G., Guyonnet, V., ... & Mench, J. A. (2013). General principles for the welfare of animals in production systems: the underlying science and its application. The Veterinary Journal, 198(1), 19-27.
(17) Baxter, E. M., Lawrence, A. B., & Edwards, S. A. (2011). Alternative farrowing systems: design criteria for farrowing systems based on the biological needs of sows and piglets. Animal, 5(4), 580-600.
(18) Portele, K., Scheck, K., Siegmann, S., Feitsch, R., Maschat, K., Rault, J. L., & Camerlink, I. (2019). Sow-Piglet Nose Contacts in Free-Farrowing Pens. Animals, 9(8), 513.
The husbandry conditions suppress the animal’s own behavior and can lead to persistent negative emotions in the animals. The resulting strain on the environment can contribute to the development of behavioral disorders (stereotypes) (19). It can happen, for example, that piglets suckle the belly of other piglets. Pigs in the fattening show stereotypical tail biting and increased agonistic, thus combative behavior (20). The sows suffer especially from the crates and often show pole biting and sham chewing (21).
In a study with sows, it could be proven that the enrichment has a direct influence on the animals. The sows were trained to expect either food or a brief fright as they approached an opening. Animals from enriched pens with manipulable material and more space subsequently approached faster in the experiments and thus reacted optimistically in contrast to animals from barren pens (22).
(19) Appleby, M. C., Olsson, A. S., & Galindo, F. (Eds.). (2018). Animal welfare. Cabi.
(20) European Food Safety Authority (EFSA). (2007). Animal health and welfare aspects of different housing and husbandry systems for adult breeding boars, pregnant, farrowing sows and unweaned piglets‐Scientific Opinion of the Panel on Animal Health and Welfare. EFSA Journal, 5(10), 572.
(21) große Beilage, E. (2020). Literaturübersicht zur Unterbringung von Sauen während Geburtsvorbereitung, Geburt und Säugezeit.
(22) Douglas, C., Bateson, M., Walsh, C., Bédué, A., & Edwards, S. A. (2012). Environmental enrichment induces optimistic cognitive biases in pigs. Applied Animal Behaviour Science, 139(1-2), 65-73.
The above examples illustrate the influence of husbandry conditions on animal health, emotions and behavior. It directly affects their life. In animal welfare work, it is therefore important to consider all dimensions equally.