Andersen IL, Bøe KE, Kristiansen AL. 1999. The influence of different feeding arrangements and food type on competition at feeding in pregnant sows. Appl Anim Behav Sci 65:91–104.
Barnett JL, Hemsworth PH, Newman EA, Mc Callum TH, Winfield CG. 1989. The effect of design of tether and stall housing on some behavioural and physiological responses related to the welfare of pregnant pigs. Appl Anim Behav Sci 24:1–12.
Bates RO, Edwards DB, Korthals RL. 2003. Sow performance when housed either in groups with electronic sow feeders or stalls. Livest Prod Sci 79:29–35.
Bohnenkamp AL, Meyer C, Müller K, Krieter J. 2013. Group housing with electronically controlled crates for lactating sows. Effect on farrowing, suckling and activity behavior of sows and piglets. Appl Anim Behav Sci 145:37–43.
Boyle LA, Leonard FC, Lynch PB, Brophy P. 2002. Effect of gestation housing on behaviour and skin lesions of sows in farrowing crates. Appl Anim Behav Sci 76:119–134.
Broom DM, Mendl MT, Zanella AJ. 1995. A comparison of the welfare of sows in different housing conditions. Anim Sci 61:369–385.
Cronin GM. 1985. The Development and Significance of Abnormal Stereotyped Behaviours in Tethered Sows. PhD Thesis. Wageningen Agricultural University; Wageningen, Netherlands:
Cronin GM, Simpson GJ, Hemsworth PH. 1996. The effects of the gestation and farrowing environments on sow and piglet behaviour and piglet survival and growth in early lactation. Appl Anim Behav Sci 46:175–192.
Dourmad JY, Etienne M, Noblet J. 1996. Reconstitution of body reserves in multiparous sows during pregnancy: Effect of energy intake during pregnancy and mobilization during the previous lactation. J Anim Sci 74:2211–2219.
Dourmad JY, Etienne M, Noblet J. 1997. Prediction de la composition chimique des truies reproductrices a partir du poids vif et de l’epaisseur de lard dorsal. J Rech Porcine Fr 29:255–262.
Eissen JJ, Kanis E, Kemp B. 2000. Sow factors affecting voluntary feed intake during lactation. Livest Prod Sci 64:147–165.
Ford SP, Christenson RK. 1979. Blood flow to uteri of sows during the estrous cycle and early pregnancy: local effect of the conceptus on the uterine blood supply. Biol Reprod 21:617–624.
Geuyen TPA, Verhagen JMF, Verstegen MWA. 1984. Effect of housing and temperature on metabolic rate of pregnant sows. Anim Prod 38:477–485.
Jensen KH, Sørensen LS, Bertelsen D, Pedersen AR, Jørgensen E, Nielsen NP, Vestergaard KS. 2000. Management factors affecting activity and aggression in dynamic group housing systems with electronic sow feeding: A field trial. Anim Sci 71:535–545.
Karlen GAM, Hemsworth PH, Gonyou HW, Fabrega E, Strom AD, Smits RJ. 2007. The welfare of gestating sows in conventional stalls and large groups on deep litter. Appl Anim Behav Sci 105:87–101.
King R. 1991. The basics of sow feeding and management. In : Proceedings Saskatchewan Pork Industry Symposium; Saskatoon, Saskatchewan, Canada. p. 47–51.
Lawrence AB, Appleby MC, Macleod HA. 1988. Measuring hunger in the pig using operant conditioning: the effect of food restriction. Anim Prod 47:131–137.
Marchant JN, Broom DM. 1996. Factors affecting posture-changing in loose-housed and confined gestating sows. J Anim Sci 63:477–485.
McGlone JJ, Borell EH, von Deen J, Johnson AK, Levis DG, Meunier-Salaün MC, Morrow J, Reeves D, Salak-Johnson JL, Sundberg PL. 2004. Compilation of the scientific literatures comparing housing systems for gestating sows and gilts using measures of physiology, behavior, performance and health. Prof Anim Sci 20:105–117.
Petersen V, Simonsen HB, Lawson LG. 1995. The effect of environmental stimulation on the development of behavior in pigs. Appl Anim Behav Sci 45:215–224.
Rampacek GB, Kraeling RR, Fonda ES, Barb CR. 1984. Comparison of physiological indicators of chronic stress in confined and nonconfined gilts. J Anim Sci 58:401–408.
Russell JA, Gosden RG, Humphreys EM, Cutting R, Fitzsimons N, Johnston S, Liddle S, Scott S, Stirland JA. 1989. Interruption of parturition in rats by morphine: a result of inhibition of oxytocin secretion. J Endocrinol 121:521–536.
SAS Institute Inc. 2008. SAS Institute Inc; User’s Guide (release 92). Cary, NC, USA:
Schmidt WE, Stevenson JS, Davis DL. 1985. Reproductive traits of sows penned individually or in groups until 35 days after breeding. J Anim Sci 60:755–759.
Scientific Veterinary Committee. 1997. The welfare of intensively kept pigs. In : Report of the cientific Veterinary Committee, Animal Welfare Section, to the Comission of the European Union. Doc. XXIV/ScVc/0005/1997; Adopted September 30, 1997; Brussels, Belgium.
Spinka M, Illmann G, Algers B, Stetkova Z. 1997. The role of nursing frequency in milk production in domestic pigs. J Anim Sci 75:1223–1228.
Spoolder HAM, Geudeke MJ, van der Peet-Schwering CMC, Soede NM. 2009. Group housing of sows in early pregnancy: a review of success and risk factors. Livest Sci 125:1–14.
Terlouw EM, Schouten WPG, Ladewig J. 1997. Physiology in Animal Welfare. Appleby C, Hughes BO, editorsCAB Int.; Oxon, New York, USA: p. 143
van Dijk AJ, van Rens BT, van der Lende T, Taverne MA. 2005. Factors affecting duration of the expulsive stage of parturition and piglet birth intervals in sows with uncomplicated, spontaneous farrowings. Theriogenology 64:1573–1590.
von Borell E, Morris JR, Hurnik JF, Mallard BA, Buhr MM. 1992. The performance of gilts in a new group housing system: Endocrinological and immunological functions. J Anim Sci 70:2714–2721.
Weary DM, Pajor EA, Fraser D, Honkanen AM. 1996. Sow body movements that crush piglets: A comparison between two types of farrowing accommodation. Appl Anim Behav Sci 49:149–158.
Weng RC, Edwards SA, Hsia LC. 2009. Effect of individual, group or ESF housing in pregnancy and individual or group housing in lactation on sow behavior. Asian Australas J Anim Sci 22:1574–1580.