(en-GB) Oliver Thring, « Is Red Tractor pork really 'high welfare'? », The Guardian, (ISSN0261-3077, lire en ligne, consulté le )
P. D. Ruen, G. D. Dial, D. D. Polson et W. E. Marsh, « Breeding and gestation facilities for swine. Matching biology to facility design », The Veterinary Clinics of North America. Food Animal Practice, vol. 8, no 3, , p. 475–502 (ISSN0749-0720, PMID1446265, lire en ligne, consulté le )
(en-US) Marc Kaufman, « Largest Pork Processor to Phase Out Crates », The Washington Post, (ISSN0190-8286, lire en ligne, consulté le )
P. D. Ruen, G. D. Dial, D. D. Polson et W. E. Marsh, « Breeding and gestation facilities for swine. Matching biology to facility design », The Veterinary Clinics of North America. Food Animal Practice, vol. 8, no 3, , p. 475–502 (ISSN0749-0720, PMID1446265, lire en ligne, consulté le )
(en-GB) Oliver Thring, « Is Red Tractor pork really 'high welfare'? », The Guardian, (ISSN0261-3077, lire en ligne, consulté le )
usda.gov
ars.usda.gov
(en) Dr. Jeremy N. Marchant-Forde, « Sow Welfare Fact Sheet - Housing and Welfare of Sows during Gestation », sur ars.usda.gov, : « The major issues surrounding the housing of sows during gestation are focused on the detrimental effects of close confinement and barren environment afforded by stalls on the one hand versus the detrimental effects of aggressive social behavior afforded by group housing on the other. »
washingtonpost.com
(en-US) Marc Kaufman, « Largest Pork Processor to Phase Out Crates », The Washington Post, (ISSN0190-8286, lire en ligne, consulté le )