Social status and previous experience in the group as predictors of welfare of sows housed in large semi-static groups

Cutaneous application of SecurePig® FLASH, a Pig appeasing pheromone analogue, facilitates adaptation and manages social behavior during feeding in semi-extensive conditions

BACKGROUND

Farm animals face several challenges throughout their lives, which can affect both their welfare and their productivity. Promoting adaptation in animals is one way of limiting these consequences. In various animal species, the use of maternal appeasing pheromones is efficient to reduce aggressiveness, improve adaptation and thus ensuring better welfare and productivity. This study sought to investigate the efficiency of a treatment with a Pig Appeasing Pheromone (PAP) on the behavior of pigs reared under semi-extensive conditions and exposed to a potential conflict- collective feeding. Animals (n = 14 divided in 2 groups of 7) were subjected to 3 different phases, (A) baseline - no pigs received the PAP, (B) SP - 2 out of the 7 pigs per group received the PAP and (C) AP- all pigs received the PAP. Behaviors related to feeding, aggression and locomotion were compared between the 3 phases of the study.

RESULTS

Compared to the baseline period, we observed that the number of head knocks was reduced when some pigs (p < 0.001) and all pigs (p < 0.005) received the PAP. Similarly, we observed that the number of fleeing attempts was reduced when some pigs (p < 0.001) and all pigs (p < 0.001) were treated when compared to baseline. This number was lower in the AP phase than in the SP phase (p < 0.001). When all pigs were treated (AP), we also observed that they spent less time investigating the floor than during the two other phases (p < 0.001), but they seemed more likely to leave the feeder due to the presence or behavior of another pig of the group (SP vs. AP, p < 0.05).

CONCLUSIONS

The PAP application improved adaptation in pigs by reducing aggressiveness and promoting conflict avoidance. Those results validate the efficiency of the pheromonal treatment under semi-extensive rearing conditions to help pigs to cope with a challenging situation. Using PAP in the pig industry seems interesting to limit unwanted consequences of farm practices on animal welfare and productivity, by promoting their adaptation.

Estimation of gestating sows' welfare status based on machine learning methods and behavioral data

Estimating the welfare status at an individual level on the farm is a current issue to improve livestock animal monitoring. New technologies showed opportunities to analyze livestock behavior with machine learning and sensors. The aim of the study was to estimate some components of the welfare status of gestating sows based on machine learning methods and behavioral data. The dataset used was a combination of individual and group measures of behavior (activity, social and feeding behaviors). A clustering method was used to estimate the welfare status of 69 sows (housed in four groups) during different periods (sum of 2 days per week) of gestation (between 6 and 10 periods, depending on the group). Three clusters were identified and labelled (scapegoat, gentle and aggressive). Environmental conditions and the sows' health influenced the proportion of sows in each cluster, contrary to the characteristics of the sow (age, body weight or body condition). The results also confirmed the importance of group behavior on the welfare of each individual. A decision tree was learned and used to classify the sows into the three categories of welfare issued from the clustering step. This classification relied on data obtained from an automatic feeder and automated video analysis, achieving an accuracy rate exceeding 72%. This study showed the potential of an automatic decision support system to categorize welfare based on the behavior of each gestating sow and the group of sows.

Are infrared thermography, feeding behavior, and heart rate variability measures capable of characterizing group-housed sow social hierarchies?

Group gestation housing is quickly becoming standard practice in commercial swine production. However, poor performance and welfare in group housed sows may result from the formation and maintenance of the social hierarchy within the pen. In the future, the ability to quickly characterize the social hierarchy via precision technologies could be beneficial to producers for identifying animals at risk of poor welfare outcomes. Therefore, the objective of this study was to investigate the use of infrared thermography (IRT), automated electronic sow feeding systems, and heart rate monitors as potential technologies for detecting the social hierarchy within five groups of sows. Behavioral data collection occurred for 12 h after introducing five sow groups (1-5; n = 14, 12, 15, 15, and 17, respectively) to group gestation housing to determine the social hierarchy and allocate individual sows to 1 of 4 rank quartiles (RQ 1-4). Sows within RQ1 were ranked highest while RQ4 sows were ranked lowest within the hierarchy. Infrared thermal images were taken behind the neck at the base of the ear of each sow on days 3, 15, 30, 45, 60, 75, 90, and 105 of the experiment. Two electronic sow feeders tracked feeding behavior throughout the gestation period. Heart rate monitors were worn by 10 randomly selected sows per repetition for 1 h prior to and 4 h after reintroduction to group gestation housing to collect heart rate variability (HRV). No differences were found between RQ for any IRT characteristic. Sows within RQ3 and RQ4 had the greatest number of visits to the electronic sow feeders overall (P < 0.04) but spent shorter time per visit in feeders (P < 0.05) than RQ1 and RQ2 sows. There was an interaction of RQ with hour for feed offered (P = 0.0003), with differences between RQ occurring in hour 0, 1, 2, and 8. Higher-ranked sows (RQ1 and RQ2) occupied the feeder for longer during the first hour than lower ranking sows (RQ3 and RQ4; P < 0.04), while RQ3 sows occupied the feeder longer than RQ1 sows during hour 6, 7, and 8 (P < 0.02). Heart beat interval (RR) collected prior to group housing introduction differed between RQ (P < 0.02 for all), with RQ3 sows exhibiting the lowest RR, followed by RQ4, RQ1, and RQ2. Rank quartile also affected standard deviation of RR (P = 0.0043), with RQ4 sows having the lowest, followed by RQ1, RQ3, and RQ2 sows. Overall, these results indicate that feeding behavior and HRV measures may be capable of characterizing social hierarchy in a group housing system.

Risk Factors for Chronic Stress in Sows Housed in Groups, and Associated Risks of Prenatal Stress in Their Offspring

Chronic stress has a detrimental effect on sow welfare and productivity, as well as on the welfare and resilience of their piglets, mediated prenatally. Despite this, the specific risk factors for chronic stress in pregnant sows are understudied. Group-housed pregnant sows continuously face numerous challenges associated with aspects of the physical (group type and size, flooring, feeding system) and social (stocking density, mixing strategy) environment. There are many well-known potent stressors for pigs that likely contribute to chronic, physiological stress, including overcrowding, hot temperatures, feed restriction, inability to forage, uncomfortable floors, and poor handling. Some of these stressors also contribute to the development of production diseases such as lameness, which in turn are also likely causes of chronic stress because of the associated pain and difficulty accessing resources. The aim of this review is to discuss potential risk factors for chronic stress in pregnant sows such as space allowance, group size and type (stable/dynamic), feeding level, lameness, pen design, feed system, enrichment and rooting material, floor type, the quality of stockmanship, environmental conditions, and individual sow factors. The mechanisms of action of both chronic and prenatal stress, as well as the effects of the latter on offspring are also discussed. Gaps in existing research and recommendations for future work are outlined.