title: Tear staining in pigs: a potential tool for welfare assessment on commercial farms.
abstract: Tear staining or chromodacryorrhea refers to a dark stain below the inner corner of the eye, caused by porphyrin-pigmented secretion from the Harderian gland. It has been shown to be a consistent indicator of stress in rats and to correlate with social stress and a barren environment in pigs. The current study was, to our knowledge, the first to test it on commercial pig farms as a potential welfare indicator. The study was carried out on three commercial farms in Finland, in connection to a larger study on the effects of different types of manipulable objects on tail and ear biting and other behavioural parameters. Farm A was a fattening farm, on which 768 growing-finishing pigs were studied in 73 pens. Farm B had a fattening unit, in which 656 growing-finishing pigs were studied in 44 pens, and a farrowing unit, in which 29 sows and their litters totalling 303 piglets were studied in 29 pens. Farm C was a piglet-producing farm, on which 167 breeder gilts were studied in 24 pens. Data collection included individual-level scoring of tear staining; scoring of tail and ear damage in the growing-finishing pigs and breeder gilts; a novel object test for the piglets; and a novel person test for the growing-finishing pigs on Farm B and the breeder gilts on Farm C. On Farm A, tear staining was found to correlate with tail damage scores (n=768, rs=0.14, P<0.001) and ear damage scores (n=768, rs=0.16, P<0.001). In the growing-finishing pigs on Farm B, tear staining of the left eye correlated with tail damage (n=656, rs=0.12, P<0.01) and that of the right eye correlated with ear damage (n=656, rs=0.10, P<0.01). On Farm A, tear-staining sores were lower in the treatment with three different types of manipulable objects as compared with controls (mean scores 3.3 and 3.9, respectively, n=31, F29=4.2, P<0.05). In the suckling piglets on Farm B, tear staining correlated with the latency to approach a novel object (n=29, rp=0.41, P<0.05). Although correlations with tail and ear damage were low, it was concluded that tear staining has promising potential as a new, additional welfare indicator for commercial pig farming. Further research is needed on the mechanisms of tear staining.
authors: 1Department of Production Animal Medicine, Faculty of Veterinary Medicine,00014 University of Helsinki,PO Box 57,Helsinki,Finland.
authors: H
authors: H
authors: Telkänranta
authors: 2USDA-ARS,LBRU,125S Russell Street,West Lafayette,IN 47907,USA.
authors: J N
authors: JN
authors: Marchant
authors: 1Department of Production Animal Medicine, Faculty of Veterinary Medicine,00014 University of Helsinki,PO Box 57,Helsinki,Finland.
authors: A
authors: A
authors: Valros
mesh_terms: D000367:Age Factors; D000822:Animal Husbandry / Q000592:standards*; D000827:Animal Welfare / Q000592:standards*; D000818:Animals; D000833:Animals, Suckling / Q000293:injuries / Q000502:physiology / Q000523:psychology; D001522:Behavior, Animal; D001733:Bites and Stings; D004431:Ear, External / Q000293:injuries; D005106:Exploratory Behavior; D005260:Female; D005387:Finland; D006243:Harderian Gland / Q000378:metabolism; D006799:Housing, Animal / Q000592:standards; D011166:Porphyrins / Q000032:analysis / Q000378:metabolism; D051381:Rats; D015203:Reproducibility of Results; D013312:Stress, Physiological / Q000502:physiology; D013315:Stress, Psychological / Q000175:diagnosis / Q000209:etiology; D013552:Swine / Q000293:injuries / Q000502:physiology* / Q000523:psychology; D013623:Tail / Q000293:injuries; D013666:Tears / Q000737:chemistry / Q000378:metabolism*
chemical_list: D011166:Porphyrins
keywords: ear biting; enrichment; pig; tail biting; tear staining