Food resources affect territoriality of invasive wild pig sounders with implications for control.

Interest in control methods for invasive wild pigs (Sus scrofa) has increased due to their range expansion, population growth, and an improved understanding of their destructive ecological and economic effects. Recent technological advances in traps for control of pig populations facilitate capture of entire social groups (sounders), but the efficacy of "whole-sounder" trapping strategies is heavily dependent on the degree of territoriality among sounders, a topic little research has explored. We assessed territoriality in wild pig sounders on the Savannah River Site, South Carolina, USA, and examined whether availability of food resources provided by a municipal-waste landfill affected among-sounder territoriality. We estimated utilization distribution overlap and dynamic interactions among 18 neighboring sounders around a landfill. We found that although neighboring sounders overlapped in space, intensity of use in shared areas was uniformly low, indicating territorial behavior. Neighbors tended to share slightly more space when closer to the landfill waste cells, indicating availability of a super-abundant resource somewhat weakens the degree of territoriality among sounders. Nevertheless, we conclude that sounders behaved in a generally territorial manner, and we discuss implications for whole-sounder trapping programs, particularly near concentrated resources such as landfills and crop fields.

Behavioral state resource selection in invasive wild pigs in the Southeastern United States.

Elucidating correlations between wild pig (Sus scrofa) behavior and landscape attributes can aid in the advancement of management strategies for controlling populations. Using GPS data from 49 wild pigs in the southeastern U.S., we used hidden Markov models to define movement path characteristics and assign behaviors (e.g., resting, foraging, travelling). We then explored the connection between these behaviors and resource selection for both sexes between two distinct seasons based on forage availability (i.e., low forage, high forage). Females demonstrated a crepuscular activity pattern in the high-forage season and a variable pattern in the low-forage season, while males exhibited nocturnal activity patterns across both seasons. Wild pigs selected for bottomland hardwoods and dense canopy cover in all behavioral states in both seasons. Males selected for diversity in vegetation types while foraging in the low-forage season compared to the high-forage season and demonstrated an increased use of linear anthropogenic features across seasons while traveling. Wild pigs can establish populations and home ranges in an array of landscapes, but our results demonstrate male and female pigs exhibit clear differences in movement behavior and there are key resources associated with common behaviors that can be targeted to improve the efficiency of management programs.

Community structure of domesticated pigs in livestock facilities.

The social structure of animal groups is considered to have an impact on their health and welfare. This could also be true for animals under commercial conditions, but research in this area has been limited. Pigs for example are known to be very social animals, but information about their grouping behavior is mostly derived from wild boars and a limited number of studies in seminatural and commercial conditions. Specifically under commercial conditions it is still unclear to what extent pig herds organize themselves in subgroups and how such group patterns emerge. To answer these questions, we tracked the positions of about 200 sows inside a barn during ongoing production over a period of five weeks and used these data to construct and analyze the animal contact networks. Our analysis showed a very high contact density and only little variation in the number of other animals that a specific animal is in contact with. Nevertheless, in each week we consistently detected three subgroups inside the barn, which also showed a clear spatial separation. Our results show that even in the high density environment of a commercial pig farm, the behavior of pigs to form differentiated groups is consistent with their behavior under seminatural conditions. Furthermore, our findings also imply that the barn layout could play an important role in the formation of the grouping pattern. These insights could be used to monitor and understand the spread of infectious diseases inside the barn better. In addition, our insights could potentially be used to improve the welfare of pigs.

The influence of early life socialisation on cognition in the domestic pig (Sus scrofa domestica).

Previously, the benefits of early-life socialisation on later-life social development have been reported in pigs. Here we investigated the effect of pre-weaning socialisation on the later-life cognitive ability of pigs using a range of techniques. Pre-weaning, 101 piglets had access to a neighbouring pen from ~ 15 days of age and interacted with non-littermates (socialised). An additional 89 piglets remained isolated within their home pen (controls). After weaning, 100 individuals were selected for a range of cognitive tests including a food reward T-maze test, reversal learning T-maze test, a social preference T-maze test, and a puzzle box test. Performance during the food reward test was not influenced by treatment. Treatment effected improvement over the course of the reversal learning test, with controls showing a significant decrease in trial duration after the first two trials. During the social preference test, socialised pigs spent significantly more time in the presence of larger stimulus pigs than controls and were quicker to leave the middle of the maze, suggesting improved social skills. Neither sex nor treatment was observed to influence pig's ability to solve the puzzle box. Thus, overall, evidence from the social preference test suggests an effect of pre-weaning socialisation on aspects of social cognitive development.

Play fighting social networks do not predict injuries from later aggression.

Early play fighting mimics later aggression in many species, and may, therefore, be expected to reduce costs from later aggressive interactions. Using social network analysis (SNA) the effect of a central play fighting network position on later skin lesions from aggression was assessed in domestic pigs. Piglets (n = 263) were kept in litter groups or socialised pre-weaning with another litter to enhance play fighting experience. Play fighting was recorded for 1.5 h per day over 6 days pre-weaning. Play fighting network centrality was quantified using measures of individual network position and entire network structure (degree, eigenvector, betweenness, clustering coefficient). Skin lesions from aggression were counted after a dyadic contest and at 24 h and 3 weeks following group mixing. Pigs with play fighting interactions with many partners experienced fewer lesions from the dyadic contest (in-degree, p = 0.01) and tended to received fewer lesions 3 weeks after group mixing (degree, p = 0.088) but no other play fighting centrality measures affected the number of lesions at any point. The benefits of play fighting were therefore limited to specific aggressive social contexts. The tendency of socialised piglets to play fight with non-littermates did not affect subsequent lesions. We advocate the use of SNA over approaches that only consider dyadic interactions to further our understanding of the influence of early social group interactions on later life experience.

Comparative analysis of the ovarian transcriptome reveals novel insights into fertility differences in Large White sows.

BACKGROUND: Fertility is the most important economic trait in sows, as it is critical for profitability. Considerable phenotypic variation in litter size exists in Large White sows. However, relatively little is known about the underlying molecular and genetic bases. OBJECTIVE: An experiment was conducted to screen key genes that affect the fecundity of pigs during the luteal (L) and follicular phases (F) of the estrous cycle. METHODS: Eight sows (n = 4 for high fertility sows and n = 4 for low fertility sows) were sacrificed on day 14 (day 1 = first day of estrus) after estrus in the L phase. Another eight sows were slaughtered on day 20 of the estrous cycle in the F phase. Sixteen ovarian tissue samples were collected at the different sacrifice time points. Total RNA extracted was used to construct the library and then sequence on an Illumina HiSeq X10 system. Differentially expressed genes (DEGs) between high and low fertility in Large White sows were identified, and their potential biological functions were analyzed using bioinformatics analysis. RESULTS: In total, 457 DEGs (161 up-regulated and 296 down-regulated genes) were detected in the ovarian tissues of the high and low fertility groups in the L phase of the estrous cycle. Furthermore, 475 DEGs (253 up-regulated and 222 down-regulated genes) were identified in the F phase. Twenty-nine DEGs were common to both comparisons. Kyoto Encyclopedia of Genes and Genomes enrichment analysis showed that the DEGs were mainly associated with steroid biosynthesis, the Hippo signaling pathway, and lysosomes. Others, such as MSMO1, CYP27B1, and CTSB, were related to reproduction. CONCLUSION: These results will contribute to a better understanding of the individual differences in fertility at the transcriptome level, which may provide useful information to explore new ways to improve fertility in pigs.

Wild boar deathbed choice in relation to ASF: Are there any differences between positive and negative carcasses?

African swine fever (ASF) is a fatal, infectious disease affecting wild boars and domestic pigs, mostly resulting in their deaths. Previous studies showed that carcasses of infected wild boars pose a serious threat for ASF virus transmission and leaving of dead bodies in the environment enables persistence of the disease in the given affected area. Therefore, the prompt finding and removal of the carcasses is crucial for effective ASF control. This study reveals habitat preferences of ASF-positive wild boars for their deathbeds, which could greatly improve the effectivity in the search for infected carcasses. The vast majority (71%) of carcasses were found in forests (although forests occupy only 26.6% of the high-risk area - Zlin region, Czech Republic), especially in young forest stands; 91.3% of infected wild boar carcasses, which were found in forests, were in stands of up to 40 years of age, where infected individuals search for calm and quiet places. The preference of younger forest stands is significantly higher for infected individuals (p < 0.001). On meadows, infected individuals preferred a higher herb layer (p = 0.002) compared to non-infected individuals. A higher preference of places more distant from roads and forest edges was observed for the infected individuals as well (p < 0.001 in both cases). No differences in deathbed habitat preference were observed between selected sex-age categories. The distance between carcasses and water source was observed to be dependent on current mean temperature. Carcasses were found closer to the water sources at higher mean temperature. Because of the comparable character of the landscape, presented models are applicable across Central Europe and have the potential to greatly facilitate the search for infected carcasses.

Effects of early and later life environmental enrichment and personality on attention bias in pigs (Sus scrofa domesticus).

We investigated effects of early and later life housing on attention bias, as an indicator of affective state, in pigs differing in coping style [reactive (LR) vs. proactive (HR)]. Pigs (n = 128) in barren or enriched housing from birth (B1 vs. E1) that experienced either a switch in housing at 7 weeks of age or not (creating B1B2, B1E2, E1E2, and E1B2 treatments), were studied in a 180-s attention bias test at 11 weeks. Pigs exposed to a 10-s-auditory-and-sudden-motion threat in the test arena paid more attention to the location of the threat, were more vigilant, showed less eating, more walking and were more likely to utter high-pitched vocalisations than non-threat pigs. During threat presence, HR pigs from post-switch enriched housing (E2-HR, i.e., B1E2 + E1E2) showed more vigilance but less exploration than others. After threat removal, no effects were found on time spent paying attention to the threat, vigilance, and eating, but E2-HR pigs paid attention to the threat more frequently, were more likely to utter high-pitched vocalisations and walked more compared to (part of) other groups, suggesting the most negative affective state in these animals. E2 pigs grunted more than B2 pigs. Thus, current housing, but not early life housing, affected behaviour in a personality-dependent manner in this attention bias test. Housing effects were opposite to expectation, possibly due to the short-term effect of the relative contrast between the home pens of the pigs and the test room. This potentially overruled putative long-term effects of environmental conditions on attention bias.

The influence of feeding behaviour on growth performance, carcass and meat characteristics of growing pigs.

This study investigated the effect of the feeding behaviour on growth performance, and carcass and meat characteristics of 96 barrows fed ad libitum or restrictively with high or low amino acids (AA) diets according to a 2 × 2 factorial design. The feeding behaviour traits were measured with automated feeders. From 86 kg BW, half of the pigs were given feeds with high indispensable (AA) contents, while the other half received feeds with indispensable AA contents reduced by 9% in early finishing (86-118 kg BW) and by 18% in late finishing (118-145 kg BW). Body lipid and protein retentions were estimated from BW and backfat depth measures recorded at the beginning and end of each period. Pigs were slaughtered at 145 kg BW and carcass and meat quality data were recorded. Phenotypic correlations among feeding behaviours, growth performances, and carcass and meat traits were computed from all the data after adjustment for the effects of feeding treatments. As feeding rate was the behavioural trait most highly correlated with performance and carcass traits, the records of each pig were classified into feeding rate tertiles. Then, the data were statistically analysed using a mixed model, which included feed restriction (FR), AA reduction (AAR), the FR × AAR interaction and the feeding rate tertile as fixed factors, and pen as a random factor. Pigs eating faster (52.1 to 118.9 g/min) had significantly greater final body weights (16%), average daily weight gains (27%), estimated protein gains (22%), estimated lipid retention (46%), carcass weights (16%), weights of lean cuts (14%), weights of fat cuts (21%), proportions of fat in the carcass (14%), and 4% lower proportions of carcass lean cuts than pigs eating slowly (12.6 to 38.2 g/min). Manipulating the eating rate, through management or genetic strategies, could affect feed intake and subsequent growth performance, hence carcass quality, but have little influence on feed efficiency.

Social network properties predict chronic aggression in commercial pig systems.

Post-mixing aggression in pigs is a harmful and costly behaviour which negatively impacts both animal welfare and farm efficiency. There is vast unexplained variation in the amount of acute and chronic aggression that dyadic behaviours do not fully explain. This study hypothesised that certain pen-level network properties may improve prediction of lesion outcomes due to the incorporation of indirect social interactions that are not captured by dyadic traits. Utilising current SNA theory, we investigate whether pen-level network properties affect the number of aggression-related injuries at 24 hours and 3 weeks post-mixing (24hr-PM and 3wk-PM). Furthermore we compare the predictive value of network properties to conventional dyadic traits. A total of 78 pens were video recorded for 24hr post-mixing. Each aggressive interaction that occurred during this time period was used to construct the pen-level networks. The relationships between network properties at 24hr and the pen level injuries at 24hr-PM and 3wk-PM were analysed using mixed models and verified using permutation tests. The results revealed that network properties at 24hr could predict long term aggression (3wk-PM) better than dyadic traits. Specifically, large clique formation in the first 24hr-PM predicted fewer injuries at 3wk-PM and high betweenness centralisation at 24hr-PM predicted increased rates of injury at 3wk-PM. This study demonstrates that network properties present during the first 24hr-PM have predictive value for chronic aggression, and have potential to allow identification and intervention for at risk groups.

Chronic intermittent stress exposure and access to grass silage interact differently in their effect on behaviour, gastric health and stress physiology of entire or castrated male growing-finishing pigs.

Entire male pigs display more aggressive and sexual behaviour. This might cause a condition of chronic stress and impair their welfare. In order to assess chronic stress in entire and castrated male pigs, as well as effects of providing grass silage as occupational and feed material on behaviour and health, we carried out a 2 × 2 × 2-factorial experiment with 147 growing-finishing pigs. Factors investigated were castration (entire/castrated), chronic intermittent social stress exposure (yes/no) and access to grass silage (yes/no), as well as their interactions. The stress exposure treatment consisted of repeated short-term confrontations and separations. We recorded different behavioural variables, circadian rhythm of salivary cortisol, response to an ACTH (adrenocorticotropic hormone) challenge test, pathological changes in the gastric mucosa and morphology of the intestinal epithelium. Stress exposure caused a decrease in posture changes and head knocks/bites in the home pen. Reference indicators affected by stress exposure did not differ between entire and castrated male pigs, indicating that there is no permanently increased baseline level of stress in entire male pigs. However, entire males responded more pronouncedly to the stress exposure compared to castrated males in terms of posture changes and play behaviour. Pigs provided with grass silage showed more play behaviour and less manipulative behaviours than pigs not receiving grass silage. Stress treated pigs had more hyperkeratosis in the gastric mucosa and gastric ulcers, while offering grass silage reduced such changes. In conclusion, our results indicate that the increased behavioural stress response of entire male pigs might require some adaptations in housing and management of entire male pigs. Gastric ulceration scoring turned out to be a potential post mortem indicator for chronic stress. Finally, providing roughages like grass silage could be a means to positively affect behaviour and gastric health in pigs.

Transcriptome differences in frontal cortex between wild boar and domesticated pig.

Animal domestication is a long-term, multistage process that results in modifications of many traits, especially the less aggressive behavior in domesticated animals. In this study, we used the Illumina RNA-seq to compare the transcriptome in brain frontal cortex between wild boar and Rongchang pig, a typical indigenous domestic pig in China, and revealed that 604 genes and 639 genes were specifically detected in wild boar and domesticated pig, respectively, with distinct functional characteristics that may be related to their respective environment. In addition, we identified 60 differentially expressed genes showing an enrichment in immune response-related function. Further comparison of the results against previous studies identified seven genes that are associated with domestication. Our results provide insights for deciphering the mechanism of pig domestication in the future.

Ontogeny of individual and litter identity signaling in grunts of piglets.

Many studies have shown that animal vocalizations can signal individual identity and group/family membership. However, much less is known about the ontogeny of identity information-when and how this individual/group distinctiveness in vocalizations arises and how it changes during the animal's life. Recent findings suggest that even species that were thought to have limited vocal plasticity could adjust their calls to sound more similar to each other within a group. It has already been shown that sows can acoustically distinguish their own offspring from alien piglets and that litters differ in their calls. Surprisingly, individual identity in piglet calls has not been reported yet. In this paper, this gap is filled, and it is shown that there is information about piglet identity. Information about litter identity is confirmed as well. Individual identity increased with age, but litter vocal identity did not increase with age. The results were robust as a similar pattern was apparent in two situations differing in arousal: isolation and back-test. This paper argues that, in piglets, increased individual discrimination results from the rapid growth of piglets, which is likely to be associated with growth and diversification of the vocal tract rather than from social effects and vocal plasticity.

The influence of experience on contest assessment strategies.

Animal contest behaviour has been widely studied, yet major knowledge gaps remain concerning the information-gathering and decision-making processes used during encounters. The mutual assessment strategy, where the individual assesses its own fighting ability (Resource Holding Potential, RHP) and compares it to that of its opponent, is least understood. We hypothesise that individuals need experience of agonistic encounters to become proficient at mutual assessment. Pigs (Sus scrofa, n = 316) were contested twice. In between contests, animals did or did not (control) receive intense fighting experience. A substantial proportion of the contests reached an outcome with a clear winner without fighting. Non-escalation was highest in RHP asymmetric dyads of the second contest, irrespective of experience. In contest 1 (no experience) and in contest 2 for the experienced animals, costs increased with loser RHP and where unaffected by winner RHP, suggesting a self-assessment strategy. In contest 2 control dyads, which only had experience of one prior contest, a negative relation between winner RHP and costs suggested mutual assessment during the pre-escalation phase but not during escalated aggression. This reveals that a brief and relatively mild experience can be beneficial in the development of mutual assessment whereas profound experience may result in adoption of a self-assessment strategy.

Pig cognitive bias affects the conversion of muscle into meat by antioxidant and autophagy mechanisms.

Slaughter is a crucial step in the meat production chain that could induce psychological stress on each animal, resulting in a physiological response that can differ among individuals. The aim of this study was to investigate the relationship between an animal's emotional state, the subsequent psychological stress at slaughter and the cellular damage as an effect. In all, 36 entire male pigs were reared at an experimental farm and a cognitive bias test was used to classify them into positive bias (PB) or negative bias (NB) groups depending on their decision-making capabilities. Half of the animals, slaughtered in the same batch, were used for a complete study of biomarkers of stress, including brain neurotransmitters and some muscle biomarkers of oxidative stress. After slaughter, specific brain areas were excised and the levels of catecholamines (noradrenaline (NA) and dopamine (DA)) and indoleamines (5-hydroxyindoleacetic acid and serotonin (5HT)) were analyzed. In addition, muscle proteasome activity (20S), antioxidant defence (total antioxidant activity (TAA)), oxidative damage (lipid peroxidation (LPO)) and autophagy biomarkers (Beclin-1, microtubule-associated protein I light chain 3 (LC3-I) and LC3-II) were monitored during early postmortem maturation (0 to 24 h). Compared with PB animals, NB pigs were more susceptible to stress, showing higher 5HT levels (P<0.01) in the hippocampus and lower DA (P<0.001) in the pre-frontal cortex. Furthermore, NB pigs had more intense proteolytic processes and triggered primary muscle cell survival mechanisms immediately after slaughter (0 h postmortem), thus showing higher TAA (P<0.001) and earlier proteasome activity (P<0.001) and autophagy (Beclin-1, P<0.05; LC3-II/LC3-I, P<0.001) than PB pigs, in order to counteract the induced increase in oxidative stress, that was significantly higher in the muscle of NB pigs at 0 h postmortem (LPO, P<0.001). Our study is the first to demonstrate that pig's cognitive bias influences the animal's susceptibility to stress and has important effects on the postmortem muscle metabolism, particularly on the cell antioxidant defences and the autophagy onset. These results expand the current knowledge regarding biomarkers of animal welfare and highlight the potential use of biomarkers of the proteasome, the autophagy (Beclin-1, LC3-II/LC3-I ratio) and the muscle antioxidant defence (TAA, LPO) for detection of peri-slaughter stress.

How much does it cost to look like a pig in a wild boar group?

Hybridization between domestic and wild species is known to widely occur and it is reported to be one of the major causes of the current biodiversity crisis. Despite this, poor attention has been deserved to the behavioural ecology of hybrids, in particular in relation to their social behaviour. We carried out a camera trap study to assess whether phenotypically anomalous colouration in wild boar, i.e. potentially introgressed with domestic pigs, affected the hierarchical structure of wild boar social groups. Chromatically anomalous wild boars (CAWs) were detected in 32 out of 531 wild boar videos. In most videos (75%) CAWs were the latest of the group, independently from their age class and group composition. Aggressions by their wild type fellows were recorded in 31.25% videos; by contrast, no aggression among wild type individuals was observed. The lack of camouflage may expose CAWs, and thus their group, to a higher predation risk, compared to wild type groups. This individual loss of local adaptation may increase predation risk by the wolf or detection by hunters, being maladaptive for the whole social group.

Young pigs exhibit differential exploratory behavior during novelty preference tasks in response to age, sex, and delay.

Novelty preference paradigms have been widely used to study recognition memory and its neural substrates. The piglet model continues to advance the study of neurodevelopment, and as such, tasks that use novelty preference will serve especially useful due to their translatable nature to humans. However, there has been little use of this behavioral paradigm in the pig, and previous studies using the novel object recognition paradigm in piglets have yielded inconsistent results. The current study was conducted to determine if piglets were capable of displaying a novelty preference. Herein a series of experiments were conducted using novel object recognition or location in 3- and 4-week-old piglets. In the novel object recognition task, piglets were able to discriminate between novel and sample objects after delays of 2min, 1h, 1 day, and 2 days (all P<0.039) at both ages. Performance was sex-dependent, as females could perform both 1- and 2-day delays (P<0.036) and males could perform the 2-day delay (P=0.008) but not the 1-day delay (P=0.347). Furthermore, 4-week-old piglets and females tended to exhibit greater exploratory behavior compared with males. Such performance did not extend to novel location recognition tasks, as piglets were only able to discriminate between novel and sample locations after a short delay (P>0.046). In conclusion, this study determined that piglets are able to perform the novel object and location recognition tasks at 3-to-4 weeks of age, however performance was dependent on sex, age, and delay.

Being a weakling and surviving: Keep the fittest siblings close-by when eating.

Weaklings serve as a buffer, allowing an increase in the overall prospect of offspring survival. Whereas birds are able to directly determine which offspring to invest in via selective feeding, multiparous mammals have fewer methods of excluding weaklings from milk provision. In pigs the maternal investment strategy is based on the vigorousness of the progeny, whereby weaklings can suffer hunger due to an inability to sufficiently stimulate the mammary gland. However, the vigorous massage might stimulate higher milk production in the surrounding glands and it is possible that a weakling's survivability is conditioned also by suckling at a position adjacent to heaviest littermate. Results of the present study have confirmed this prediction, showing that the surviving weaklings tended to have the heaviest littermates as nearest neighbours during suckling. It appears, therefore, that weaklings which establish a type of commensal, rather than competitive, relationship with strongest siblings might increase their survivability.

Mood and personality interact to determine cognitive biases in pigs.

Cognitive bias has become a popular way to access non-human animal mood, though inconsistent results have been found. In humans, mood and personality interact to determine cognitive bias, but to date, this has not been investigated in non-human animals. Here, we demonstrate for the first time, to the best of our knowledge, in a non-human animal, the domestic pig (Sus scrofa domesticus), that mood and personality interact, impacting on judgement. Pigs with a more proactive personality were more likely to respond optimistically to unrewarded ambiguous probes (spatially positioned between locations that were previously rewarded and unrewarded) independent of their housing (or enrichment) conditions. However, optimism/pessimism of reactive pigs in this task was affected by their housing conditions, which are likely to have influenced their mood state. Reactive pigs in the less enriched environment were more pessimistic and those in the more enriched environment, more optimistic. These results suggest that judgement in non-human animals is similar to humans, incorporating aspects of stable personality traits and more transient mood states.

A preliminary study of the effects of individual response to challenge tests and stress induced by humans on learning performance of weaned piglets (Sus scrofa).

This study investigated whether individual behavioural characteristics of piglets and stress induced by experience with humans can influence learning performance. After weaning, piglets received a chronic experience with humans to modulate their emotional state: rough (ROU), gentle (GEN), or minimal (MIN) experience. Simultaneously, they were trained on a discrimination task. Afterward, their behaviour during challenge tests was assessed. The first learning step of the task involved associating a positive sound cue with a response (approach a trough) and success of piglets depended mostly on motivation to seek for reward. Although the experience with humans did not have direct effect, the degree of fear of handler, measured based on their reactivity to a human approach test, was related to motivation to seek rewards and learning speed of this first step in stressed ROU piglets, but not in MIN and GEN piglets. In contrast, the second learning step was more cognitively challenging, since it involved discrimination learning, including negative cues during which piglets had to learn to avoid the trough. Locomotion activity, measured during an open-field test, was associated with performance of the discrimination learning. To conclude, fearfulness towards humans and locomotion activity are linked with learning performance in relation to task complexity, highlighting the necessity to take into account these factors in animal research and management.