Welfare Implications of Gestation Sow Housing

​Literature Review

January 31, 2014

THE ISSUE

Sows can be kept in different types of housing during pregnancy. Three main categories of housing are discussed below, along with their key advantages and disadvantages in relation to sow welfare. While the general categories of gestation stall, group pen, and free-range system can be identified, there is considerable variation within each of these categories. Welfare outcomes are not only a product of interactions between housing type and sow, but involve many other factors, such as stockmanship, genetics, sows’ previous experience, feeding practices, flooring and bedding types, and climate.1
 
The use of gestation stalls has become increasingly controversial.1,2 Legislative and ballot initiatives in some US states have limited their use. In addition, current or scheduled bans on gestation stall use are in place in many countries although the implementation of those bans is uneven.Some
major foodservice companies, distributors and retailers have indicated their intent to purchase from producers who do not use gestation stalls. Consumer acceptance of the gestation stall, as demonstrated by responses to surveys and during focus groups, is often found to be lower4,5,6 with preference shown
for products from non-gestation stall systems.7 However, it is unclear how well consumer intent translates to purchasing behavior. 

GESTATION STALL

A gestation stall is an individual pen. Dimensions vary but are typically approximately 6.5 feet long and 2.5 feet wide, to allow the sows to lie on their side without their udders protruding from the stall.8,9 Facilities with older installations may include stalls of narrower widths. 

Advantages

Individual Access to Resources—Stall housing allows each sow to be given an individually tailored diet10,11 and secure access to water. Enrichment materials, such as straw or balls, chains and ropes also may be provided, although this is not common in most installations.
Accessibility—In facilities providing front and rear alleys for viewing sows, individual housing makes it easy to identify, inspect and intervene on behalf of specific sows, such as for veterinary treatment.1,10
Protection from Aggression—Stall-housed sows are unlikely to receive injuries associated with physical aggression, but agonistic interactions may still occur between adjacent animals.12

Disadvantages

Behavioral Restriction— Stall-housed sows are less active,13 and spend more time sitting and standing and less time walking than sows housed in pens.11 Sows in gestation stalls can stand-up and lie down, but are prevented from turning around and performing behaviors such as communal lying and movement to preferred microenviroments.
Confinement Injuries—Stall-housed sows may have a higher incidence of injuries such as pressure sores, ulcers, and abrasions.14,15,16 
Stereotypy—Sows in stalls may perform more stereotypic behaviors such as biting, chewing, licking and rubbing than sows housed in the other systems.11,17,18,19 
  

Refinements

Stalls can be improved by providing straw20 or mats.21 Stall design can also be modified to allow turning22 and/or to provide more space, and larger accommodations are associated with lower injury rates for larger sows.25
 

GROUP PEN

Group pens are enclosures that hold a group of sows.  They vary considerably in design with indoor pens on slatted floors being the predominant system in the United States. Alternative systems such as hoop barns26 or with straw bedding16 are also available in suitable climates. Across various systems, group sizes range from four or five pigs to more than two hundred.

Advantages

Behavioral Opportunities—Grouped sows have increased behavioral opportunities, such as the ability to move around the enclosure27 and opportunities for full body social interactions.

Disadvantages

Aggression Injuries—Because grouped sows can make full body contact, scratch and bite injuries14,16,23,28 and, sometimes, lameness29 are more common, especially for subordinate sows.30,31  Aggression injuries are associated with the addition of novel sows to the pen,1 competition for resources,1 and crowding32.
Body Condition—If competition for feed is not well-controlled dominant sows may become overweight and middle-ranking and subordinate sows underweight.1,33,34,35 

Refinements

Additional benefits may be conferred by providing environmental enrichments. For example provision of straw20 and manipulable objects36 supports investigative behaviors and may also reduce aggression and reduce rates of injuries.
 
Aggression resulting from mixing usually lasts for about two days, and can be reduced by appropriate management such as forming and maintaining stable groups,37 grouping sows similar in size,38 and providing sub-areas in the pens (e.g., with walls) and/or room to retreat (depending on system this may be  7 feet, 3 inches35,39,40,41,42 or more31 per sow). Providing a source of fiber44 or satiety-inducing diet or feeding ad libitum for the first 48 hours may also reduce aggression.
 
Feed must be delivered by a system that manages competition for food among sows to avoid high levels of aggression.  These systems include:
  • Simultaneously feeding in multiple areas within the pen to limit the ability of dominant sows to monopolize food.33
  • Simultaneous feeding into stanchions or free access stalls, to allow all sows to eat without harassment. Free-access stalls can also provide a retreat space for subordinate sows. Feeding of tailored diets is possible with manual feeding.35
  • Using an electronic sow feeder that admits sows one at a time and provides a tailored diet based on a radio-frequency identification tag (RFID) inserted into the sow’s ear.43
  • Using multiple feedings spaced closely together in time so that dominant sows became satiated and other sows can access food.44
  • Trickle feeding so that all feeding sites are equally attractive and aggression would be unproductive.10

 

FREE RANGE

Free range is defined as sows having access to an outdoor area for at least 80% of their production cycle.45,46

Advantages

Reduced Aggression— Space allowance in outdoor housing systems is generally larger so aggression between sows is less likely to occur.
Behavioral Opportunities—Depending on the system, free-range sows may have additional behavioral opportunities, such as grazing, rooting soil and wallowing.
Noise/Ammonia—In contrast to indoor housing, outdoor areas will provide reduced exposure to machine noise47 and have less accumulation of ammonia.48

Disadvantages

Parasites—Sows with outdoor access tend to have more parasites,49 such as helminths.50
Other Environmental Hazards—Depending on the location, sows may be more exposed to climatic extremes, predation, disease vectors and other hazards.

Refinements

Free-range systems may require refinements that allow swine to cope with extremes of temperature, such as wallowing areas51 and/or deep bedded pens.
 

NON-DISTINGUISHING FINDINGS

Many traditional welfare indicators do not consistently favor one housing system over another. These include: measures of stress1,11,24 (e.g. cortisol) and overall productivity.10,11,28 Some welfare outcomes vary between systems due to specific variables, such as lameness that is high when bedding is not provided, regardless of enclosure size and type.11
 

SUMMARY

Gestation sow housing systems vary in their advantages and disadvantages regarding the welfare of the sow. When comparing housing systems for pregnant sows, making a definitive welfare judgment requires assigning weights to an array of contributing welfare indicators including, but not limited to, type, severity and incidence of injuries; behavioral and social opportunities; and exposure to parasites, disease, and harmful or aversive stimuli. As no universally accepted weighting system exists, there is no clear consensus as to which is the superior system across all situations. However, the public is generally more critical of gestation stall housing than other systems, which has led to voluntary and mandatory transition to alternative housing systems by some producers.1 As such there is an ongoing need to develop an array of housing systems that suit local conditions,42 effectively provide enhanced opportunities for the sows to move and interact socially, and avoid an unacceptable increase in negative outcomes such as injury associated with aggression1 or exposure to environmental hazards.
   

Visual Summary 

REFERENCES

 

 1. McGlone J J, Salak-Johnson J. Changing from sow gestation crates to pens: Problem or opportunity? In Proceedings Manitoba Swine Seminar, Winnipeg, Manitoba, Canada. 2008;47-53.
 2. Marchant-Forde JN. The welfare of pigs. Vol. 7. Springer, 2009.
 3. Tuyttens FA, Van Gansbeke S, Ampe B. Survey among Belgian pig producers about the introduction of group housing systems for gestating sows. J Anim Sci 2011;89:845-55.
 4. Tonsor GT, Wolf C, Olynk N. Consumer voting and demand behavior regarding swine gestation crates. Food Policy 2009;34:492-498.
 5. Ryan, E. Public attitudes towards housing systems for pregnant pigs. Master’s Thesis, University of British Columbia, 2013.
 6. Tonsor, G. T., Olynk, N., & Wolf, C. (2009). Consumer preferences for animal welfare attributes: The case of gestation crates. J Agr Appl Econ 2009;41:713-730.
 7. Norwood FB, Lusk JL. A calibrated auction-conjoint valuation method: valuing pork and eggs produced under differing animal welfare conditions. J Environ Econ Manag 2011;62: 80-94.
 8. Li YZ, Gonyou HW. Effects of stall width and sow size on behaviour of gestating sows. Can J Anim Sci 2007;87:129-138.
 9. McGlone JJ, Vines B, Rudine AC et al. The physical size of gestating sows. J Anim Sci 2004;82: 2421-2427.
10. Schoening J. Group sow performance; comparing three group housed systems to conventional stalls, in Proceedings. Feeding group-housed sows and the growing herd efficiency, 44th AASV Annual Meeting 2013;127-130.
11.  McGlone JJ. Review: Updated scientific evidence on the welfare of gestating sows kept in different housing systems. Prof Anim Scientist 2013;29:189-198.
12. Marchant-Forde JN. Social behavior in swine and its impact on welfare, in Proceedings. 21st IPVS Congress 2010;36-39.
13. Andronie I, Nadronie V, Parvu M et al. Behavior and productive performance of pregnant sows according to housing system. Bull Univ Agric Sci Vet Med Cluj Napoca 2012;67:12-16.
14. Gjein H, Larssen RB. Housing of pregnant sows in loose and confined systems--a field study 1. Vulva and body lesions, culling reasons and production results. Acta Vet Scand 1995;36:185.
15. Boyle LA, Leonard FC, Lynch PB et al. Effect of gestation housing on behaviour and skin lesions of sows in farrowing crates. Appl Anim Behav Sci 2002;76:119-134.
16. Karlen GAM, Hemsworth PH, Gonyou HW et al. The welfare of gestating sows in conventional stalls and large groups on deep litter. Appl Anim Behav Sci 2007;105:87-101.
17. Vieuille-Thomas C, Le Pape G, Signoret JP. Stereotypies in pregnant sows: indications of influence of the housing system on the patterns expressed by the animals. Appl Anim Behav Sci 1995;44:19-27.
18.Broom DM, Mendl MT, Zanella AJ A comparison of the welfare of sows in different housing conditions. Animal Science 1995;61:369-386.
19. Chapinal N, Ruiz de la Torre JL, Cerisuelo A et al. Evaluation of welfare and productivity in pregnant sows kept in stalls or in 2 different group housing systems. J Vet Behav Clin Appl Res 2010;5: 82-93.
20. Tuyttens FAM. The importance of straw for pig and cattle welfare: A review. Appl Anim Behav Sci 2005;92:261-282.
21. Tuyttens FAM, Wouters F, Struelens E et al. Synthetic lying mats may improve lying comfort for gestating sows. Appl Anim Behav Sci 2008;114:76–85.
22. McFarlane JM, Boe KE, Curtis SE. Turning and walking by gilts in modified gestation crates. J Anim Sci 1988;66:326.
23. Gonyou HW. Experiences with alternative methods of sow housing. J Am Vet Med Assoc 2005;226:1336 – 3340.
24. Becker B, Christenson R, Ford J et al. Serum cortisol concentrations in gilts and sows housed in tether stalls, gestation stalls and individual pens. Ann Rech Vet 1984;15:237-242.
25. Anil L, Anil SS, Deen J.  Evaluation of the relationship between injuries and size of gestation stalls relative to size of sows. J Am Vet Med Assoc 2002;221:834–836.
26. Lammers PJ, Honeyman MS, Mabry JW et al. Performance of gestating sows in bedded hoop barns and confinement stalls. J Anim Sci 2007;85:1311-1317.
27. Weng RC, Edwards SA, Hsia LC. Effect of individual, group or ESF housing in pregnancy and individual or group housing in lactation on sow behavior. Asian-Aust J Anim Sci 2009;22:1574-1580.
28. Séguin MJ, Friendship RM, Kirkwood RN et al. Effects of boar presence on agonistic behaviour, shoulder scratches, and stress response of bred sows at mixing. J Anim Sci 2006;84:1227–1237.
29. Harris MJ, Pajor EA, Sorrells AD et al. Effects of stall or small group gestation housing on the production, health and behaviour of gilts. Livest Sci 2006;102:171-179.
30. Tönepöhl B, Appel AK., Voß B et al. Interaction between sows’ aggressiveness post mixing and skin lesions recorded several weeks later. Appl Anim Behav Sci 2013;144:108-115 .
31. Remience V, Wavreille J, Canart B et al. Effects of space allowance on the welfare of dry sows kept in dynamic groups and fed with an electronic sow feeder. Appl Anim Behav Sci 2008;112:284-296.
32. Anil L, Anil S, Deen J et al. Effect of group size and structure on the welfare and performance of pregnant sow in pens with electronic sow feeders. Can J Anim Sci 2006;70:128–136.
33. Craig JV. Pregnant sow behavior when housed in groups and singly. Report of progress (Kansas State University. Agricultural Experiment Station and Cooperative Extension Service); 422 (2010).
34. Damm BI. Loose housing of sows–is this good welfare? Acta Vet Scand 2007;50:S9.
35. Edwards S. Balancing sow and piglet welfare with production efficiency. In proceedings London Swine Conference 2008;17-30.
36. Andronie I, Pârvu M, Andronie V et al. The welfare of gestating sows in different housing. Anim Sci Biotech 2010;43:280-283.
37. Anil L, Anil SS, Deen J et al. Effect of group size and structure on the welfare and performance of pregnant sows in pens with electronic sow feeders. Can J Vet Res 2006;70:128.
38. Gonyou HW Group housing: alternative systems, alternative management. Adv Pork Prod 2003;14:10-107.
39. Salak-Johnson JL, Niekamp SR, Rodriguez-Zas SL et al. Space allowance for dry, pregnant sows in pens: body condition, skin lesions and performance. J Anim Sci 2007;85:1758–1769.
40. Spoolder HAM, Geudeke MJ, Van der Peet-Schwering CMC et al. Group housing of sows in early pregnancy: A review of success and risk factors. Livest Sci 2009;125:1-14.
41. Whittaker AL, Van Wettere WH, Hughes PE. Space Requirements to Optimize Welfare and Performance in Group Housed Pigs-A Review. Am J Anim Vet Sci 2012;7:48-54.
42. Kemp B, Soede NM. Reproductive Issues in Welfare‐Friendly Housing Systems in Pig Husbandry: A Review. Reprod Domest Anim 2012;47:51-57.
43. Katz J, Horback K, Parsons T. Use of daily feeding order at an electronic sow feeder (ESF) to improve the individual animal care of group housed sows. Feeding group-housed sows and the growing herd efficiency, 44th AASV Annual Meeting, San Diego California. March 3, 2013.
44. Newton B. Formulating diets for sows in group housing: What should be considered? Feeding group-housed sows and the growing herd efficiency, 44th AASV Annual Meeting, San Diego California. March 3, 2013.
45. Bracke MBM, Metz JHM, Spruijt BM et al. Overall welfare assessment of pregnant sow housing systems based on interviews with experts. Neth J Agric Sci 1999;47:93-104.
46. Buckner LJ, Edwards SA, Bruce JM. Behaviour and shelter use by outdoor sows. Appl Anim Behav Sci 1998;57:69-80.
47. Zurbrigg, K. The effects of noise level in gestation barns on human hearing loss and swine reproduction.  Available at http://www.prairieswine.com/the-effects-of-noise-level-in-gestation-barns-on-human-hearing-loss-and-swine-reproduction. Accessed May 28, 2013.
48. Scipioni R, Martelli G, Volpelli LA. Assessment of welfare in pigs. Ital J Anim Sci 2009;8:117-136.
49. van der Giessen J, Fonville M, Bouwknegt M et al. Seroprevalence of Trichinella spiralis and Toxoplasma gondii in pigs from different housing systems in The Netherlands. Vet Parasitol 2007;148:371-374.
50. Nansen P, Roepstorff A. Parasitic helminths of the pig: factors influencing transmission and infection levels. Int J Parasitol 1999;29:877-891.
51. Miao ZH, Glatz PC, Ru YJ. Review of production, husbandry and sustainability of free-range pig production systems. Asian-australas J Anim Sci 2004:17:1615-163

 
This information has been prepared as a service by the American Veterinary Medical Association’s Animal Welfare Division.
 
Mention of trade names, products, commercial practices or organizations does not imply endorsement by the American Veterinary Medical Association.

 © 2014 American Veterinary Medical Association