Anxiety Behavior in Pigs (Sus scrofa) Decreases Through Affiliation and May Anticipate Threat

Witness for resolution: post-conflict quadratic affiliation in semi-free ranging pigs

In social mammals, post-conflict resolution can involve the reunion of former opponents (reconciliation), spontaneous/solicited post-conflict affiliation of a third party with either opponent (triadic contacts), and affiliation between other individuals (hereafter bystanders; quadratic contacts). Quadratic contacts-possibly informing complex cognitive abilities-have been neglected in post-conflict studies. We investigated quadratic affiliation in semi-free ranging pigs Sus scrofa, at the ethical farm Parva-Domus (Cavagnolo, Italy). Kinship was known. We collected behavioral data on adult pigs (n = 104) via video recordings (43 h) followed by video analyses. Affiliative and anxiety behaviors between bystanders were collected under post-conflict (PC; following a conflict between non-bystanders) and matched-control (MC; no conflict) conditions. Quadratic affiliation was present in pigs, as bystanders affiliated more in PC than MC, and such affiliation was followed by a decrease in the anxiety behaviors of both the interacting bystanders. Thus, quadratic contacts may be partly aimed at reducing one's own anxiety (intrinsic regulation). Quadratic affiliation was highest between closely related bystanders, which suggests that such affiliation may be most effective when close kin is involved. Quadratic affiliation was lowest after reconciliation and spontaneous triadic contacts. This suggests that direct peacemaking between opponents and spontaneous triadic contacts with close kin may most likely replace quadratic affiliation. Hence, pigs can be influenced by the negative events that affect other pigs-but not themselves-and their response may be modulated by social factors. Such non-random quadratic affiliation may point toward the presence of elements of social appraisal abilities in pigs.

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.

Sows' Responses to Piglets in Distress: An Experimental Investigation in a Natural Setting

Domestic pigs (Sus scrofa) possess complex socio-cognitive skills, and sows show high inter-individual variability in maternal behaviour. To evaluate how females-reared under natural conditions-react to the isolation calls of their own piglets or those of other females, we conducted observations and experimental trials. In January-February 2021, we conducted all-occurrences sampling on affiliation, aggression, and lactation (daily, 7:30-16:30 h) on six lactating and four non-lactating females at the ethical farm Parva Domus (Turin, Italy). The trials (30 s each, n = 37/sow) consisted of briefly catching and restraining a piglet. We recorded the sow response (none/reactive/proactive movement towards the piglet; self-directed anxiety behaviours such as body shaking) before and during the trial and under control conditions. Increased levels of anxiety behaviour in sows were accompanied by an increased frequency of responses. Less aggressive sows and lactating sows showed the highest frequencies of response. Finally, the isolation calls' maximum intensity had an influence on the type of response observed, with higher proactive response frequencies following lower intensity isolation calls. Our results suggest that being under lactation could play a key role in increasing sow response levels and that specific acoustic features may influence the response.

Domestic pigs (Sus scrofa) engage in non-random post-conflict affiliation with third parties: cognitive and functional implications

In social mammals, conflict resolution involves the reunion of former opponents (aggressor and victim) after an aggressive event (reconciliation) or post-conflict triadic contacts with a third party, started by either opponent (solicited-TSC) or spontaneously offered by the third party (unsolicited-TUC). These post-conflict strategies can serve different functions, including consolation (specifically when TUCs reduce the victim's anxiety). We investigated the possible presence and modulating factors of such strategies on semi-free ranging pigs (Sus scrofa; N = 104), housed at the ethical farm Parva Domus (Cavagnolo, Italy). Kinship was known. Reconciliation was present and mainly occurred between weakly related pigs to possibly improve tolerant cohabitation. Triadic contacts (all present except aggressor TSCs) mostly occurred between close kin. TSCs enacted by victims reduced neither their post-conflict anxiety behaviors nor further attacks by the previous aggressor, possibly because TSCs remained largely unreciprocated. TUCs towards aggressors did not reduce aggressor post-conflict anxiety but limited aggression redirection towards third parties. TUCs towards the victim reduced the victim but not the third-party's anxiety. However, TUCs may also provide inclusive fitness benefits to third parties by benefiting close kin. In sum, pigs engaged in non-random solicited/unsolicited triadic contacts, which suggests that pigs might possess socio-emotional regulation abilities to change their own or others' experience and elements of social appraisal, necessary to detect the emotional arousal of relevant others and (in case of TUCs) take the agency to restore homeostasis.

Effect of Enrichment Items on the Physiology and Behavior of Sows in the Third Trimester of Pregnancy

Modern intensive pig breeding harms animal welfare, which is especially noticeable for pregnant sows kept in confinement stalls. This study aimed to evaluate the effects of enrichment items on the movement and physiological parameters of sows in the third trimester of pregnancy. A total of 30 large white pregnant sows were randomly divided into three equal treatment groups (n = 10): control, pine wood, and scented wood groups. Interestingly, compared with the control group, the sows in the pine wood or scented wood groups showed less ventral lying and more lateral lying behavior (p < 0.01), coupled with significant reduction in the frequency of scratching and sham-chewing (p < 0.01), but with no significant difference in the degree of preference for these enrichment items (p > 0.05). Additionally, the sows in the pine wood or scented wood groups also decreased significantly in the concentration of immunoglobulin A (IgA) (p < 0.01) and the concentration of tumor necrosis factor-α (TNF-α) (p < 0.05) throughout the late pregnancy period. Overall, adding enrichment items to confinement stalls can alleviate the chronic stress and the stereotypic behavior of sows, suggesting their potential to reduce welfare compromise.

Using a behaviour random permutation model to identify displacement grooming in ungulates

Behaviour affects an individual’s life in all aspects, e.g., enhancing fitness, leveraging predation risk, and reducing competition with conspecifics. However, the sequential distribution of behaviours received less attention and is unclear what the function of displacement behaviour is. Displacement activities can be found in vertebrate species but there is no formal method to determine whether a behaviour is expressed as a displaced or normal activity. Analysing the sequential distributions of behaviours in a natural setting may allow researchers to identify unexpected distributions as a possible signature of displacement activities. In this study, we used a behaviour random permutation model to detect the presence of a displacement activity in the Tibetan antelope Pantholops hodgsonii and the Tibetan gazelle Procapra picticaudata. The results showed that grooming in both ungulates tended to be accompanied with vigilance, and the frequency of grooming after vigilance was significantly higher than before vigilance. A significant positive correlation between the scan rate and grooming rate in the two ungulates was obtained. We suggest that grooming could sometimes be expressed as a displacement activity in ungulates. In addition to providing a general method for further research on displacement activities in a variety of animal species, this study sheds light on the importance of a spectral analysis of sequential distribution of animal behaviours. Behaviour random permutation models can be used to explore the relevance between any two behaviours in a specific sequence, especially to identify a myriad of unexpected behaviours relative to their normal context of occurrence.

Loss of diurnal behavioral rhythms and impaired lipid metabolism in growing pigs with mistimed feeding

The misalignment of eating time and the endogenous circadian rhythm impairs the body's ability to maintain homeostasis. Although it is well established that children and growing animals differ from adults in their energy metabolism and behavioral patterns, little is known about how mistimed feeding disturbs the diurnal rhythms of behavior and metabolism in children and growing diurnal animals. In this study, growing pigs (diurnal animal) were randomly assigned to the daytime-restricted feeding (DRF) and nighttime-restricted feeding (NRF) groups for 5 weeks. Compared with observations in the DRF group, NRF disrupted the diurnal rhythm of behavior and clock genes and lowered the serum ghrelin, dopamine, and serotonin levels during the daytime and nighttime. Microbiome analysis results suggested that NRF altered the diurnal rhythm and composition of the gut microbiota, and increased log-ratios of Catenibacterium:Butyrivibrio and Streptococcus:Butyrivibrio. Based on the serum proteome, the results further revealed that rhythmic and upregulated proteins in NRF were mainly involved in oxidative stress, lipid metabolism, immunity, and cancer biological pathways. Serum physiological indicators further confirmed that NRF decreased the concentration of melatonin and fibroblast growth factor 21 during the daytime and nighttime, increased the diurnal amplitude and concentrations of very-low-density lipoprotein cholesterol, triglyceride, and total cholesterol, and increased the apolipoprotein B/ApoA1 ratio, which is a marker of metabolic syndrome. Taken together, this study is the first to reveal that mistimed feeding disrupts the behavioral rhythms of growing pigs, reprograms gut microbiota composition, reduces the serum levels of hormones associated with fighting depression and anxiety, and increases the risk of lipid metabolic dysregulation.