Tear staining in finisher pigs and its relation to age, growth, sex and potential pen level stressors

Abstract

Tear staining (TS) in the pig has been related to different stressors and may be a useful tool for assessing animal welfare on farm. The aim of the current study was to investigate TS across the finisher period and its possible relation to age, growth, sex and experimentally induced stressors. The study included 80 finisher pens divided between three batches. Within each batch, the pens either included pigs with docked or undocked tails, had straw provided (150 g/pig/day) or not and had a low (1.21 m2/pig, 11 pigs) or high stocking density (0.73 m2/pig, 18 pigs). Tear staining (scores 1 to 4; from smaller to larger tear stain area, respectively) and tail damage were scored on each individual pig three times per week over the 9-week study period, and the individual maximum TS score within each week was chosen for further analysis. Data were analysed using logistic regression separately for each of the four possible TS score levels. The TS scores 1 and 2 decreased with weeks into the study period and were negatively related to the average daily gain (ADG) of the pigs, whereas the TS score 4 increased with weeks into the study period and was positively related to ADG. None of the TS scores differed between females and castrated males, and neither straw provision nor lowering the stocking density affected the TS scores. However, the TS score 1 decreased the last week before an event of tail damage (at least one pig in the pen with a bleeding tail wound), whereas the TS score 4 increased. The results of the current study advocates for a relation between TS and the factors such as age, growth and stress in the pig, while no relation was found between TS and the environmental factors straw provision and lowered stocking density. The relations to age and growth are important to take into consideration if using TS as a welfare assessment measure in the pig in the future.

On-Farm Welfare Assessment Protocol for Suckling Piglets: A Pilot Study

“…Therefore, the higher score in tear staining on F1 was not in accordance with the results of the other welfare parameters. This could suggest that other factors, not considered in the present study, could have had an impact on tear staining (e.g., dustiness, gas concentration, dirtiness) as previously suggested [ 60 ].…”

“…Tear staining resulted significantly higher in F1 compared to F2. Increased tear staining was associated with increased stress in the late rearing phase, in finisher pigs [ 60 ]. The same Author also reported that tear staining was linked to tail lesions, as was also observed by Telkänranta et al [ 31 ] in growing-finishing pigs, while Parois et al [ 61 ] found tear staining to be associated with skin lesions in weaned piglets.…”

Towards Facial Expression Recognition for On-Farm Welfare Assessment in Pigs

“…Along with the region of the actual eye and eyelids, the region below the tear-ducts seems to feature predominantly. This may be due to the presence of tear staining, which has been suggested as an indicator of negative welfare in pigs [30] but so far has not been validated as an indicator of stress [31]. The input image is also included for easier comparison above each heatmap.…”

Behavior and Welfare of Undocked Heavy Pigs Raised in Buildings with Different Ventilation Systems

“…In pigs, it has been proposed as an indicator of negative emotional state because of a correlation with processing negative emotions [ 20 , 42 ]. Other studies have hypothesized that tear staining might also be stimulated by excessive gas concentration, dustiness, pen soiling, or other environmental conditions [ 24 , 43 ]. On this observation day, the MV building group showed a higher proportion of dirty pigs.…”