Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-10T15:35:38.812Z Has data issue: false hasContentIssue false
  • English
  • Français

Review of wallowing in pigs: implications for animal welfare

Published online by Cambridge University Press:  01 January 2023

MBM Bracke  and
HAM Spoolder
MBM Bracke*
Affiliation:
Wageningen Livestock Research, Wageningen University and Research Centre, PO Box 65, 8200 AB Lelystad, The Netherlands
HAM Spoolder
Affiliation:
Wageningen Livestock Research, Wageningen University and Research Centre, PO Box 65, 8200 AB Lelystad, The Netherlands
*
* Contact for correspondence and requests for reprints: Marc.Bracke@wur.nl
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Most modern production systems, especially in temperate climates, do not offer wallowing facilities to pigs and, to date, this has neither generated much concern in welfare science nor public debate on pig welfare. Nevertheless, wallowing is a natural behaviour of pigs which may be important to them. This paper systematically examines the overall importance of wallowing for pig welfare using principles developed in semantic modelling. As a first step, relevant citations were collected from the scientific literature. Secondly, since the importance of the attribute (‘wallowing’) is dependent upon the discrepancy between its best and worst levels, these levels were specified in relation to the status quo in pig husbandry, ie no pool (even during periods of overheating) and the ideal mud pool, respectively. Criteria for an ideal mud pool were formulated in terms of pool location and size, substrate, thermal conditions, body care and hygiene. Thirdly, available scientific information about wallowing was systematically described in relation to ten so-called weighting categories identified in semantic modelling (pain and illness, survival/heat stress, fitness, stress, aggression, abnormal behaviour, frustration, natural behaviour, preferences and demand). Fourthly, the welfare importance of wallowing was assessed by tentatively comparing it to several other welfare attributes, such as food, foraging substrate, social contact and non-castration. This leads to the suggestion that wallowing is important for pig welfare because of its multifaceted nature. It may even be very important when other forms of thermoregulation are sub-optimal. This paper, finally, discusses the ‘ethical room for manoeuvre’ concerning the (non-) implementation of mud pools in practice. An integrated approach is suggested to address related scientific, technological and ethical issues, because stakeholders are faced not only with scientific and technological gaps in knowledge but also with economical, ecological, food-safety and psychological barriers. As an important element of natural behaviour and positive welfare, the subject may provide an opportunity for pig farming. This should be recognised more explicitly in transition processes towards fully sustainable pig production systems.

Keywords

animal welfareethicsnatural behaviourpigssemantic modellingwallowing behaviour
Type
Research Article
Information
Animal Welfare , Volume 20 , Issue 3 , August 2011 , pp. 347 - 363
Copyright
© 2011 Universities Federation for Animal Welfare

References

Abell, T 1947 Shade trees and windbreaks on the pig farm [in Queensland]. Queensland Agricultural Journal 65: 74–84Google Scholar
Adam, A 1984 Gruppenhaltung von leerstehenden und tragenden Sauen in Auslaufen sowie Einzelhaltung von ferkelfuhrenden Sauen in geraumigen Buchten. PhD Thesis, Ludwig-Maximilians-University, Műnchen, Germany. [Title translation: Group housing of pregnant and non-pregnant sows in yards and individual housing of suckling sows in large pens]Google Scholar
Andresen, N and Redbo, I 1999 Foraging behaviour of growing pigs on grassland in relation to stocking rate and feed crude protein level. Applied Animal Behaviour Science 62: 183–197CrossRefGoogle Scholar
Anonymous 2001 Scientists’ assessment of the impact of housing and management on animal welfare. Journal of Applied Animal Welfare Science 4: 3–52CrossRefGoogle Scholar
Anindita Panja Patel, M, Kumar, A, Singh, SK and Sanjay Kumar, K 2008 Effect of different heat stress ameliorating measures on the growth performance of weaned piglets. Indian Journal of Animal Production and Management 24: 55–58Google Scholar
Anindita Panja Patel, M, Kumar, A, Korde, JP and Singh, SK 2009 Effect of different heat stress ameliorating measures on the enzymes, minerals and hormones of piglets. Indian Veterinary Journal 86: 713–715Google Scholar
Bate, LA and Hacker, RR 1985 Effect of cannulation and environmental temperature on the concentration of serum cortisol in pregnant sows. Canadian Journal of Animal Science 65: 399–404CrossRefGoogle Scholar
Belden, RC and Pelton, MR 1976 Wallows of the European wild hog in the mountains of east Tennessee. Journal of Tennessee Academic Sciences 51: 91–93Google Scholar
Boissy, A, Manteuffel, G, Jensen, MB, Oppermann, MR, Spruijt, B, Keeling, LJ, Winckler, C, Forkman, B, Dimitrov, I, Langbein, J, Bakken, M, Veissier, I and Aubert, A 2007 Assessment of positive emotions in animals to improve their welfare. Physiology and Behavior 92: 375–397CrossRefGoogle ScholarPubMed
Bracke, MBM 2007 Multifactorial testing of enrichment criteria: pigs ‘demand’ hygiene and destructibility more than sound. Applied Animal Behaviour Science 107: 208–232CrossRefGoogle Scholar
Bracke, MBM 2008 RICHPIG: a semantic model to assess enrichment materials for pigs. Animal Welfare 17: 289–304Google Scholar
Bracke, MBM 2010 Zoelen van Varkens en Implicaties voor Dierenwelzijn. Wageningen UR Livestock: Lelystad, The Netherlands. Available at: http://www.livestock research.wur.nl/NL/publicaties/Publicaties_Livestock_Research/. [Title translation: Wallowing in pigs and its implications for animal welfare]Google Scholar
Bracke, MBM 2011 Review of wallowing in pigs: description of the behaviour and its motivational basis. Applied Animal Behaviour Science 132: 1–13CrossRefGoogle Scholar
Bracke, MBM, Edwards, SA, Metz, JHM, Noordhuizen, JPTM and Algers, B 2008 Synthesis of semantic modelling and risk analysis methodology applied to animal welfare. Animal 2: 1061–1072CrossRefGoogle ScholarPubMed
Bracke, MBM, Hulsegge, B, Keeling, L and Blokhuis, HJ 2004 Decision support system with semantic model to assess the risk of tail biting in pigs: 1. Modelling. Applied Animal Behaviour Science 87: 31–44CrossRefGoogle Scholar
Bracke, MBM, Spruijt, BM and Metz, JHM 1999 Overall welfare assessment reviewed. Part 1: Is it possible? Netherlands. Journal of Agricultural Science 47: 279–291Google Scholar
Bracke, MBM, Spruijt, BM, Metz, JHM and Schouten, WGP 2002a Decision support system for overall welfare assessment in pregnant sows A: Model structure and weighting procedure. Journal of Animal Science 8: 1819–1834CrossRefGoogle Scholar
Bracke, MBM, Metz, JHM, Spruijt, BM and Schouten, WGP 2002b Decision support system for overall welfare assessment in pregnant sows B: validation by expert opinion. Journal of Animal Science 8: 1835–1845CrossRefGoogle Scholar
Bracke, MBM, Zonderland, JJ, Lenskens, P, Schouten, WGP, Vermeer, H, Spoolder, HAM, Hendriks, HJM and Hopster, H 2006 Formalised review of environmental enrichment for pigs in relation to political decision making. Applied Animal Behaviour Science 98: 165–182CrossRefGoogle Scholar
Bray, CJ and Singletary, CB 1948 Effect of hog wallows on gains of fattening swine. Journal of Animal Science 7: 521–522Google Scholar
Buckner, LJ, Edwards, SA and Bruce, JM 1998 Behaviour and shelter use by outdoor sows. Applied Animal Behaviour Science 57: 69–80CrossRefGoogle Scholar
Butler, DR 1995 Zoogeomorphology: Animals as Geomorphic Agents. Cambridge University Press: New York, USACrossRefGoogle Scholar
Callaway, TR, Morrow, JL, Johnson, AK, Dailey, JW, Wallace, FM, Wagrom, EA, McGlone, JJ, Lewis, AR, Dowd, SE, Poole, TL, Edrington, TS, Andreson, RC, Genovese, KJ, Byrd, JA, Harvey, RB and Nisbet, DJ 2005 Environmental prevalence and persistence of Salmonella spp. in outdoor swine wallows. Foodborne Pathogens and Disease 2: 263–273CrossRefGoogle ScholarPubMed
Campbell, TA and Long, DB 2009 Feral swine damage and damage management in forested ecosystems. Forest Ecology and Management 257: 2319–2326CrossRefGoogle Scholar
Cornelissen, J, de Greef, K, Kaal-Lansbergen, L, de Lauwere, C, Ursinus, N, Vermeer, H, van Weeghel, E and Zonderland, J 2009 Projectteam ‘Diergericht Ontwerpen voor varkens’ 2009 Wat wil het varken? Brochure. Wageningen UR: Lelystad, The Netherlands. Available at: www.varkansen.nlGoogle Scholar
Culver, AA, Andrews, FN, Conrad, JH and Noffsinger, TL 1960 Effectiveness of water sprays and a wallow on the cooling and growth of swine in a normal summer environment. Journal of Animal Science 19: 421–428CrossRefGoogle Scholar
Curtis, SE and Stricklin, WR 1991 The importance of animal cognition in agricultural animal production systems: an overview. Journal of Animal Science 69: 5001–5007CrossRefGoogle ScholarPubMed
Danish Pig Production 2007 Facts on Animal Welfare. Available at: http://danishpigproduction.dk/Annual_reports/index.aspx?id=23c24f1b-fff9-4632-aacd-6081c5528eb9. (Accessed 19-05-2010)Google Scholar
Dawkins, MS 1983 Battery hens name their price: consumer demand theory and the measurement of ethological ‘needs’. Animal Behaviour 31: 1195–1205CrossRefGoogle Scholar
Day, GE 1915 Productive Swine Husbandry. JB Lippincott: Philadelphia, USAGoogle Scholar
De Greef, K, de Jong-Timmerman, M, Schouten, W, ten Hoope, B and Groenestein, K 2003 Het Varkensmagazine, Dierenwelzijn in de Toekomst. Varkenswensen voor Varkensstallen. Modern: Bennekom, The Netherlands. [Title translation: The pig magazine. Animal welfare in the future. Pig preferences for pig barns]Google Scholar
Dellmeier, GR and Friend, TH 1991 Behavior and extensive management of domestic sows (Sus scrofa) and litters. Applied Animal Behaviour Science 29: 327–341CrossRefGoogle Scholar
Dettweiler F and Muller 1924 Lehrbuch der Schweinezucht. DLG-Verlag: Berlin, Germany. [Title translation: Teaching book of pig breeding]Google Scholar
Dickson, JG, Mayer, JJ and Dickson, JD 2001 Wild hogs. In: Dickson, JG (ed) Wildlife of Southern Forests: Habitat and Management pp 191–208. Hancock House Publishers: Blaine, WA, USAGoogle Scholar
Driessen, C 2007 Stacking pigs: Dutch pig tower debates and the changing nature of ethical livestock production. In: Zollitsch, W, Winckler, C, Waiblinger, S and Haslberger, A (eds) Sustainable Food Production and Ethics pp 219–233. Wageningen Academic Publishers: Wageningen, The NetherlandsGoogle Scholar
EFSA 2007a Scientific report on animal health and welfare in fattening pigs in relation to housing and husbandry. Annex to the EFSA Journal 564: 1–14Google Scholar
EFSA 2007b Scientific report on the risks associated with tail biting in pigs and possible means to reduce the need for tail docking considering the different housing and husbandry systems (Question No EFSA-Q-2006-029). The EFSA Journal 611: 2–98Google Scholar
FAWC 2009 Farm Animal Welfare in Great Britain: Past, Present and Future. Farm Animal Welfare Council: Millbank, London, UKGoogle Scholar
Fernández-Llario, P 2005 The sexual function of wallowing in male wild boar (Sus scrofa). Journal of Ethology 23: 9–14CrossRefGoogle Scholar
Frädrich, H 1967 Das verhalten der schweine (Suidae, Tyassuidae und Flusspferde [Hippopotamidae]). In: Kükenthal, W (ed) Handbook of Zoology VIII, 42 pp 270–314. De Gruyter: Berlin, Germany. [Title translation: The behaviour of pigs]Google Scholar
Frädrich, H 1969 Varkens en Pecari's. In: Grzimek, B (ed) Het Leven Der Dieren Encyclopedie van het dierenrijk pp 78–110. Het Spectrum: Utrecht, The Netherlands. [Title translation: The life of animals, encyclopedia of the animal kingdom]Google Scholar
Fraser, AF 1970 Studies on heat stress in pigs in a tropical environment. Tropical Animal Health and Production 2: 76–86CrossRefGoogle Scholar
Garrett, WN, Bond, TE and Kelly, CF 1960 Environmental comparisons of swine performance as affected by shaded and unshaded wallows. Journal of Animal Science 19: 921–925CrossRefGoogle Scholar
Gegner, L 2001 Considerations in organic hog production. ATTRA's Organic Matters Series pp 43. Available at: http://www.organicagcentre.ca/Docs/ATTRA/hog_production2001.pdf. (Accessed 13-05-2010)Google Scholar
Gnanaraj, PT, Sivaskumar, T, Murugan, M and Kumararaj, R 2008 Effect of different types of wallowing on the performance of large white Yorkshire. Indian Journal of Animal Sciences 78: 663–664Google Scholar
Gosling, LM and McKay, HV 1990 Scent-rubbing and status signalling by male mammals. Chemoecology 1: 92–95CrossRefGoogle Scholar
Graves, HB 1984 Behavior and ecology of wild and feral swine (Sus scrofa). Journal of Animal Science 58: 482–492CrossRefGoogle Scholar
Hacker, RR, Ogilvie, JR, Morrison, WD and Kains, F 1994 Factors affecting excretory behavior of pigs. Journal of Animal Science 72: 1455–1460CrossRefGoogle ScholarPubMed
Heitman, H Jr and Hughes, EH 1949 The effects of air temperature and relative humidity on the physiological well-being of swine. Journal of Animal Science 8: 171–181CrossRefGoogle Scholar
Heitman, H Jr, Bond, TE, Kelly, CF and Hahn, L 1959 Effect of modified summer environment on swine performance. Journal of Animal Science 18: 1367–1372CrossRefGoogle Scholar
Heitman, H Jr, Hahn, L, Bond, TE and Kelly, CF 1962 The effects of modified summer environment of swine behavior. Animal Behaviour 10: 15–19CrossRefGoogle Scholar
Henry, SC and Tokach, LM 1995 Eimeria-associated pathology in breeding gilts. Swine Health and Production 3: 200–201Google Scholar
Heutinck, LFM and Driessen, C 2010 De dynamiek in de melkvee-ethiek. V-focus 1: 22–23. [Title translation: The dynamics in the dairy ethics]Google Scholar
Hörning, B, Raskopf, S, Simantke, C, Boehnke, E, Walter, J and Schneider, M 1999 Argemäße Schweinehaltung. Grundlagen und Beispiele aus der Praxis. Stiftung Ökologie & Landbau: Bad Dürkheim, Germany. [Title translation: Species-suited pig husbandry. Principles and examples from practice]Google Scholar
Horrell, RI, A’Ness, PJ, Edwards, SA and Eddison, JC 2001 The use of nose-rings in pigs: consequences for rooting, other functional activities, and welfare. Animal Welfare 10: 3–22Google Scholar
Hsia, LC, Fuller, MF and Koh, FK 1974 Sprinkling on the performance of growing and finishing pigs during hot weather. Tropical Animal Health Production 6: 183–187CrossRefGoogle Scholar
Huynh, TTT, Aarnink, AJA, Gerrits, WJJ, Heetkamp, MJH, Cahn, TT, Spoolder, HAM, Kemp, B and Verstegen, MWA 2005 Thermal behaviour of growing pigs in response to high temperature and humidity. Applied Animal Behaviour Science 91: 1–16CrossRefGoogle Scholar
Huynh, TTT, Aarnink, AJA, Truong, CT, Kemp, B and Verstegen, MWA 2006 Effects of tropical climate and water cooling methods on growing pigs’ responses. Livestock Science 104: 278–291CrossRefGoogle Scholar
Huynh, TTT, Aarnink, AJA, Heetkamp, MJH, Verstegen, MWA and Kemp, B 2007 Evaporative heat loss from group-housed growing pigs at high ambient temperatures. Journal of Thermal Biology 32: 293–299CrossRefGoogle Scholar
Imes, M 1920 Hog Lice and Hog Mange. Methods of Control and Eradication. Farmers’ Bulletin 1085, May 1920. US Department of Agriculture: Washington DC, USAGoogle Scholar
Ingram, DL 1965 Evaporative cooling in pig. Nature 207: 415–416CrossRefGoogle ScholarPubMed
Jackson, AD 1938 Fattening hogs need concrete wallow in hot weather. Progress Report. Texas Agricricultural Experimental Station, Texas A&M University: College Station, TX, USAGoogle Scholar
Jenn-Chung Hsu 2009 Effect of water bath on growth performance, blood traits and health of pigs. Thesis, National Chung Hsing University, Department of Animal Science, China. Available at: http://ir.lib.nchu.edu.tw/handle/309270000/26676. (Accessed 13-05-2010)Google Scholar
Jensen, P 2002 Behaviour of pigs. In: Jensen, P (ed) The Ethology of Domestic Animals: An Introductory Text pp 159–172. CABI Publishing: Wallingford, Oxon, UKCrossRefGoogle Scholar
Jensen, P and Toates, FM 1993 Who needs ‘behavioural needs’? Motivational aspects of the needs of animals. Applied Animal Behaviour Science 37: 161–181CrossRefGoogle Scholar
Johnson, AK, Mitloehner, FM, Morrow, JL and McGlone, JJ 2008 Effects of shaded versus unshaded wallows on behavior, performance, and physiology of the outdoor lactating sow. Journal of Animal Science 86: 3628–3634CrossRefGoogle ScholarPubMed
Kaller, MD and Kelso, WE 2006 Swine activity alters invertebrate and microbial communities in a coastal plain watershed. American Midland Naturalist 156: 163–177CrossRefGoogle Scholar
Kikuta, AH and Stone, CP 1986 Food preferences of captive feral pigs: a preliminary report. In: Smith, CW (ed) Proceedings of the Sixth Conference in Natural Sciences pp 27–38. 10-13 June 1986, Hawaiian Volcanoes National Park, Hawaii, USAGoogle Scholar
Korthals, M 2004 Before Dinner: Philosophy and Ethics of Food. Springer: Dordrecht, The NetherlandsCrossRefGoogle Scholar
Korthals, M 2008a Ethical traceability and ethical room for manoeuvre. In: Coff, C, Barling, D, Korthals, M and Nielsen, T (eds) The International Library of Environmental, Agricultural and Food Ethics Ethical Traceability and Communicating Food pp 251–256. Springer: Dordrecht, The NetherlandsCrossRefGoogle Scholar
Korthals, M 2008b Ethical rooms for manoeuvre and their prospects vis-à-vis the current ethical food policies in Europe. Journal of Agricultural and Environmental Ethics 21: 249–273CrossRefGoogle Scholar
Lassen, J, Sandøe, P and Forkman, B 2006 Happy pigs are dirty! Conflicting perspectives on animal welfare. Livestock Science 103: 221–230CrossRefGoogle Scholar
Lawrence, A 1987 Consumer demand theory and the assessment of animal welfare. Animal Behaviour 35: 293–294CrossRefGoogle Scholar
Leenstra, FR, Visser, EK, Ruis, MAW, de Greef, KH, Bos, AP, van Dixhoorn, ID and Hopster, H 2007 Ongerief bij rundvee, varkens, pluimvee, nertsen en paarden. Rapport 71. Animal Sciences Group: Lelystad, The NetherlandsGoogle Scholar
LNV 2007 Nota Dierenwelzijn. LNV: The Hague, The Netherlands. Available at: http://www.minlnv.nl/portal/page?_pageid=116,1640321&_dad=portal&_schema=PORTAL&p_fìle_id=22066. (Accessed 16-06-2010). [Title translation: Policy note on animal welfare]Google Scholar
Mason, GJ, Cooper, J and Clarebrough, C 2001 Frustrations of fur-farmed mink: mink may thrive in captivity but they miss having water to romp about in. Nature 401: 35–36CrossRefGoogle Scholar
Mayda, C 2004 Pig pens, hog houses and manure pits: a century of change in hog production. Material Culture 36: 18–42Google Scholar
McGlone, JJ 1999 Managing heat stress in outdoor pigs. Presented at Symposium on Outdoor Pig Production. Brazil, September 1999. Available at: http://www.depts.ttu.edu/porkindustry institute/research/MANAGING%20HEAT%20STRES%20IN%20OUTDOOR%20PIGS.htm. (Accessed 01-05-2010)Google Scholar
Mosquera, J, Hol, JMG, Winkel, A, Nijeboer, GM, Ogink, NWM and Aarnink, AJA 2010a Fijnstofemissie uit stallen: Dragende zeugen. Rapport 294. Wageningen UR Livestock Research: Lelystad, The Netherlands. [Title translation: Dust emission from animal houses: pregnant sows]Google Scholar
Mosquera, J, Hol, JMG, Winkel, A, Nijeboer, GM, Ogink, NWM and Aarnink, AJA 2010b Fijnstofemissie uit stallen: Vleesvarkens. Rapport 292. Wageningen UR Livestock Research: Lelystad, The Netherlands. [Title translation: Dust emission from animal houses: growing and finishing pigs]Google Scholar
Mount, LE 1979 Adaptation to Thermal Environment: Man and His Productive Animals. Edward Arnold Limited, Thomson Litho Ltd: East Kilbride, UKGoogle Scholar
Olsen, AW, Dybkjær, L and Simonsen, HB 2001 Behaviour of growing pigs kept in pens with outdoor runs II. Temperature regulatory behaviour, comfort behaviour and dunging preferences. Livestock Production Science 69: 265–278CrossRefGoogle Scholar
Olsson, IAS and Keeling, LJ 2005 Why in earth? Dustbathing behaviour in jungle and domestic fowl reviewed from a Tinbergian and animal welfare perspective. Applied Animal Behaviour Science 93: 259–282CrossRefGoogle Scholar
Roseline, JA, Mathew, J, Murugan, M, Davis, J and Saseendran, PC 2008 Influence of management system on stress in pigs by assessing faecal cortisol. Tamilnadu Journal of Veterinary and Animal Sciences 4: 108–109Google Scholar
Rydhmer, L, Lundström, K and Andersson, K 2010 Immunocastration reduces aggressive and sexual behaviour in male pigs. Animal 4: 965–972CrossRefGoogle ScholarPubMed
Sambraus, HH 1981 Das suhlen von sauen. Deutsche Tierarztliche Wochenschrift 88: 65–67. [Title translation: Wallowing of sows]Google Scholar
Schmid, L 1963 Zucht, Futterung und Haltung der Schweine. DLG-Verlag: Frankfurt, Germany. [Title translation: Breeding, feeding and husbandry of pigs]Google Scholar
Smith, HJ and Hawkes, AB 1978 Kidney worm infection in feral pigs in Canada with transmission to domestic swine. The Canadian Veterinary Journal 19: 40–43Google ScholarPubMed
Sowls, LK 1984 The Peccaries. University of Arizona Press: Tucson, USAGoogle Scholar
Spinka, M 2006 How important is natural behaviour in animal farming systems? Applied Animal Behaviour Science 100: 117–128CrossRefGoogle Scholar
Spinka, M 2009 Domestication effects on animal emotional signalisation: a conceptual model. Proceedings of the UFAW International Symposium 2009 on Darwinian Selection, Selective Breeding and the Welfare of Animals. University of Bristol, Bristol, UK. Available at: http://www.ufaw.org.uk/documents/SPEAKER-ABSTRACTS2009_000.pdf. (Accessed 24-08 2010)Google Scholar
Stegeman, LC 1938 The European Wild Boar in the Cherokee National Forest, Tennessee. Journal of Mammalogy 19: 279–290CrossRefGoogle Scholar
Steinbach, J 1970 Effect of wallows on diurnal and gestational variations in the respiratory frequency of pregnant sows. Respiration Physiology 10: 64–73CrossRefGoogle ScholarPubMed
Stevens, RL 1996 The Feral Hog in Oklahoma. Samuel Roberts Noble Foundation: Ardmore, OK, USAGoogle Scholar
Stolba, A and Wood-Gush, DGM 1989 The behaviour of pigs in a seminatural environment. Animal Production 48: 419–425Google Scholar
SVC (Scientific Veterinary Committee) 1997 The Welfare of Intensively Kept Pigs. Report to the Directorate General XXIV of the European Commission. Document XXIV/ScVc/0005/9. Adopted 30th September 1997. Scientific Veterinary Committee, Animal Welfare Section: Brussels, BelgiumGoogle Scholar
Tidwell, AL and Fletcher, JL 1951 The effect of summer environment on the body temperature and respiration rate of swine. Journal of Animal Science 10: 523–532CrossRefGoogle ScholarPubMed
Tynes, VV 1999 Potbellied pig husbandry and nutrition. Veterinary Clinics of North America, Exotic Animal Practice 2: 193–208CrossRefGoogle ScholarPubMed
Ursinus, WW, Schepers, F, de Mol, RM, Bracke, MBM, Metz, JHM and Groot Koerkamp, PWG 2009 COWEL: a decision support system husbandry systems for dairy cattle on welfare. Animal Welfare 18: 454–552Google Scholar
Van der Mheen, HW and Spoolder, HAM 2005 Designated rooting areas to reduce pasture damage by pregnant sows. Applied Animal Behaviour Science 95: 133–142CrossRefGoogle Scholar
Van der Peet, GFV, van der Veen, HB and van Leeuwen, H 2010 Monitoring integraal duurzame stallen. Peildatum 1 januari 2010. Rapport 370. Wageningen UR Livestock Research: Lelystad, The Netherlands. [Title translation: Monitoring integrally sustainable animal housing, reference date January 1, 2010]Google Scholar
Van Eijk, ONM, de Lauwere, CC, van Weeghel, HJE, Lansbergen, LMTE, Miedema, AMMA, Ursinus, WW, Janssen, APHM, Cornelissen, JMR and Zonderland, JJ 2010a Varkansen. De Pagode, de Pijler en de Parel. Wageningen UR Livestock Research: Lelystad, The Netherlands. [Title translation: The pagode, the pillar and the pearl]Google Scholar
Van Eijk, ONM, de Lauwere, CC, van Weeghel, HJE, Lansbergen, LMTE, Ursinus, WW, Cornelissen, JMR, Zonderland, JJ, Miedema, AMMA and Jansen, APHM 2010b Varkansen: Springplank naar een Duurzame Veehouderij: Varkenshouderij met Neus voor Dier, Ondernemer, Milieu en Burger-Consument. Wageningen UR Livestock Research: Lelystad, The Netherlands. [Title translation: Springboard to sustainable livestock farming: pig husbandry with a nose for the animal, entrepreneur, environment and citizen-consumer]Google Scholar
Van Putten, G 2000 An ethological definition of animal welfare with special emphasis on pig behaviour. Proceedings of the Second NAHWOA Workshop 2000. Available at: http://www.sopa.org.uk/_cms/files/An_ethological_definition_of_animal_welfare_with_special_emphasis_on_pig_behaviour.170.pdf. (Accessed 03-05-2010)Google Scholar
Verbeke, W 2009 Stakeholder, citizen and consumer interests in farm animal welfare. Animal Welfare 18: 325–333Google Scholar
Verburg, G 2008 Toekomstvisie op de veehouderij pp 8. Letter from the Minister of Agriculture, Nature and Food Quality to the Dutch parliament, 18 January 2008. Available at: http://www.minlnv.nl/portal/page?_pageid=116,1640321&_dad=portal&_schema=PORTAL&p_file_id=24405. (Accessed 10-06-2010). [Title translation: Vision on the future of livestock farming]Google Scholar
Vestergaard, KS and Bjerg, B 1996 Wallowing behaviour in fattening pigs. Proceedings of the 30th International Congress of the International Society for Applied Ethology p 66. 14-17 August 1996, University of Guelph, Ontario, CanadaGoogle Scholar
Wechsler, B and Bachmann, I 1998 A sequential analysis of eliminative behaviour in domestic pigs. Applied Animal Behaviour Science 56: 29–36CrossRefGoogle Scholar
Willeberg, P 1991 Animal welfare studies: epidemiological considerations. Proceedings of the Society for Veterinary Epidemiology and Preventive Medicine pp 76–82. London, UKGoogle Scholar
Zonderland, JJ 2010 Talking tails, quantifying the development of tail biting in pigs. PhD Thesis, Wageningen University, Wageningen, The NetherlandsGoogle Scholar
Zonderland, JJ and Enting, J 2004 Varkenshouderij in Brazilië. Sterke Integrates en Stevige Merken. Praktijkrapport Varkens 48. Animal Sciences Group: Lelystad, The Netherlands. [Title translation: The Pig Production Chain in Brazil]Google Scholar