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Simple Summary: In marine coral reef ecosystems, anemonefish are a group with highly complex behavioral patterns and strict social hierarchies. However, there has been a paucity of research on the factors associated with stable hierarchical relationships or the behaviors performed during competitive interactions, especially in anemonefish in the growth phase before sexual differentiation. In the present study, we employed an observational approach to assess the personality type of each individual by observing the interactive behavior between unsexually differentiated Amphiprion clarkii. Our findings revealed that the personality of A. clarkii varied significantly between individuals, with two main types. Furthermore, our pairing experiments confirmed the impact of personality on the establishment of a stable social hierarchy. These personality-related behavioral traits are potentially important for both individual and population survival, and extend our understanding of the establishment and evolution of social hierarchies in anemonefish and their impact on population dispersal. Furthermore, they have the potential to guide aquaculture practices. In this study, the behavioral ethogram of Amphiprion clarkii during the growth phase prior to sexual differentiation was summarized based on behavioral observations in three social environments. These behaviors can be classified into four categories: in addition to normal behaviors, the other three categories of behaviors—threatening, agonistic, and appeasing behaviors—represent different intentions in interactions with other individuals. Subsequently, the personalities of each individual were assessed by testing their reactions to intruders. These individuals mainly exhibited two distinct personality types: bold-aggressive and shy-submissive. In pairing experiments, the interactive behaviors of the anemonefish were observed in pairing combinations of different body sizes and personalities. The impact of personality on the establishment of a stable social hierarchy was confirmed by significant differences in the success rates of different pairing combinations, with the frequency of appeasing behaviors being the main factor influencing the success rate. Our results suggested that in natural waters, when juvenile individuals migrate among host anemones, shy-submissive individuals are more likely to be accepted due to their appeasing behaviors towards larger individuals, thus avoiding the risk of being attacked and bitten, and benefiting the survival of the individual. Conversely, bold-aggressive individuals are more likely to be driven away to another host anemone due to their unwillingness to settle for a lower-ranked status, thereby contributing to population dispersal and increasing opportunities for gene exchange between populations. [ABSTRACT FROM AUTHOR]

Simple Summary: In recent years, the interest in virtual fencing systems for flexible animal enclosure management has increased. However, implementing such systems requires significant investment due to the need for individual collars, hindering large-scale adoption. This study examines the spatial distribution of a cow herd using GPS locations from the Nofence© system, aiming to minimize the number of collars required by identifying patterns in positions and ranks to derive a hierarchy. Contrary to expectations, no distinct pattern emerged, suggesting future studies should focus on individual interactions rather than viewing the herd as a single unit. Interest in virtual fencing has increased due to its flexibility for agriculture and rewilding. However, systems like Nofence© require large financial investments, and the need for individual collars complicates large-scale use. If cattle herds maintain cohesive groups around leading individuals, fewer collars could be used, thereby enhancing cost efficiency. This study investigates the pattern in spatial distribution in a herd of 17 Angus cows on Fanø in Denmark with GPS locations, using a Nofence© system. The aim of this paper is to determine how individuals position themselves in a herd, spatially, and identify a pattern in ranks. The method used in this study examines the distances between an individual to the rest of the herdmates using nearest neighbour and descriptive statistics. Contrary to expectations, this study did not reveal a distinct pattern in herd distribution. While some tendencies in spatial distribution patterns were observed, only a low concordance could be found ( W = 0.15 , p < 0.001 ), indicating great variability in the cattle's ranks. A cumulative curve of the ranks estimated over the entire periods, however, allowed a rough estimation of the hierarchy and allowed identification of the highest-ranked cows, making the use of a cumulative curve a possible solution to finding the high-ranked cows. This research underscores the complexity of cattle social structures and highlights the need for extended observation periods and alternative methodologies to enhance the cost-effectiveness and scalability of virtual fencing in agricultural and rewilding contexts. [ABSTRACT FROM AUTHOR]

Simple Summary: The vomeronasal organ is essential for chemical communication in many species, particularly in pigs, in which the establishment of a social hierarchy in groups is crucial. Alterations to the vomeronasal organ have been shown to be linked to aggressive behaviors in this species. Moreover, it was recently demonstrated in a mouse model that the environmental air composition can impact the condition of the vomeronasal organ. As pigs can be farmed in intensive and free-range farming conditions, the aim of this study was to analyze whether the porcine farming method influences the condition of the vomeronasal organ using a histological approach. The results showed that pigs housed in free-range farming conditions exhibited more alterations in their vomeronasal organs than did those housed in intensive conditions. The vomeronasal organ (VNO) plays a key role in mammals, since it detects pheromones thus enabling social interactions between congeners. VNO inflammatory changes have been shown to severely impact animal life, leading to impaired social interactions in groups, such as in pigs. Environmental air is known to be strongly modified in farms, and it is suspected to be one of the causes of this alteration. This study aimed to compare via histology the VNOs of pigs housed in intensive conditions (n = 38) to those of pigs housed in free-range farming conditions (n = 35). VNO sections were stained in hematoxylin and eosin to assess the presence of nonsensory and sensory epithelium alterations and collagenolysis. The nonsensory epithelium was significantly more inflamed in animals in free-range farming conditions than those in intensive conditions (p < 0.0001) and was more strongly affected by signs of collagenolysis (p < 0.0001). The sensory epithelium seemed to be less altered by the different environmental conditions (p = 0.7267). These results suggest that species-typical pig behaviors, such as digging and rooting for food, could facilitate the presence of microparticles in the oral cavity and their entrance into the vomeronasal canals, leading to changes to the VNO. [ABSTRACT FROM AUTHOR]

Simple Summary: In this study, a deep learning-based detection and identification method is proposed to detect and identify the movement duration and aggressive behavior of pigs under on-farm conditions by using computer vision technology and electronic identity cards. The performance of different target detection algorithms for individual pig and aggressive behavior detection is also evaluated. The aim of this study is to establish an automated system for detecting pig aggressive behavior and energy expenditure, which may be able to provide reliable data and technical support for the study of the social hierarchy of pigs, as well as the selection and breeding of pig health and aggression phenotypes. Motion and aggressive behaviors in pigs provide important information for the study of social hierarchies in pigs and can be used as a selection indicator for pig health and aggression parameters. However, relying only on visual observation or surveillance video to record the number of aggressive acts is time-consuming, labor-intensive, and lasts for only a short period of time. Manual observation is too short compared to the growth cycle of pigs, and complete recording is impractical in large farms. In addition, due to the complex process of assessing the intensity of pig aggression, manual recording is highly influenced by human subjective vision. In order to efficiently record pig motion and aggressive behaviors as parameters for breeding selection and behavioral studies, the videos and pictures were collected from typical commercial farms, with each unit including 8~20 pigs in 7~25 m2 space; they were bred in stable social groups and a video was set up to record the whole day's activities. We proposed a deep learning-based recognition method for detecting and recognizing the movement and aggressive behaviors of pigs by recording and annotating head-to-head tapping, head-to-body tapping, neck biting, body biting, and ear biting during fighting. The method uses an improved EMA-YOLOv8 model and a target tracking algorithm to assign a unique digital identity code to each pig, while efficiently recognizing and recording pig motion and aggressive behaviors and tracking them, thus providing statistics on the speed and duration of pig motion. On the test dataset, the average precision of the model was 96.4%, indicating that the model has high accuracy in detecting a pig's identity and its fighting behaviors. The model detection results were highly correlated with the manual recording results (R2 of 0.9804 and 0.9856, respectively), indicating that the method has high accuracy and effectiveness. In summary, the method realized the detection and identification of motion duration and aggressive behavior of pigs under natural conditions, and provided reliable data and technical support for the study of the social hierarchy of pigs and the selection of pig health and aggression phenotypes. [ABSTRACT FROM AUTHOR]

Simple Summary: The need to establish a social hierarchy represents a period of severe stress for sows when they are introduced into new groups because of the associated aggressive behavior. The aim of this study was to determine the effect of providing access to straw in racks and manila ropes (IMPROVED) on aggressive behavior after mixing, compared to a typical minimal enrichment gestation system (CONTROL), and to understand the effect of parity order and backfat on the level of the aggression. The overall average number of fights and the initiated aggressive behavior in the three observation days were greater in the CONTROL pens, although within time, we found a significant effect of treatment only on the number of fights performed 3 weeks post-mixing. The effect of backfat thickness revealed an effect only on the observations of initiated aggressive behavior, which was most frequently performed by sow with a low backfat thickness. Parity order did not have a significant effect on the display of any of the aggressive behaviors. These results suggest that aggression at mixing is unavoidable and, indeed, is essential to ensuring the establishment of the dominance hierarchy and thereby achieving group stability. Nevertheless, optimal enrichment materials could have a beneficial effect on at least reducing its frequency. For sows introduced into new groups, the aggressive behavior associated with establishing a social hierarchy represents a period of severe stress. The aim of this study was to investigate the effect of providing sows with an improved pen environment (straw in racks and ropes) on aggressive behavior after mixing and to understand the role played by sow back fat thickness and parity order. At 29 d post-service, sows were mixed into IMPROVED or CONTROL pens with individual feeding stalls (6 groups/treatment, 20 sows/group). Aggressive behavior was recorded for 2 h at mixing (T0) and 24 h (T1) and 3 weeks post-mixing (T21). Overall, the sows in the CONTROL pens performed more fighting behavior compared to the IMPROVED sows (p < 0.001). This difference was significant only at T21 (p < 0.001). Additionally, the sows in the CONTROL pens generally initiated more aggressive behaviors than the sows in the IMPROVED pens (p = 0.02). The sows with a low back fat thickness initiated more aggressive behaviors, but parity had no significant effect on any of the aggressive behaviors. These results indicate a beneficial effect of improvements to the pen environment on the aggression performed by group-housed sows between the time of mixing and three weeks later. The effect was reduced on the day of mixing, which is in accordance with the necessity for sows to employ aggression to establish the dominance hierarchy. [ABSTRACT FROM AUTHOR]

Simple Summary: Black rockfish (Sebastes schlegelii) are naturally solitary animals. Under a high stocking density in aquaculture, juvenile black rockfish frequently show aggressive interactions, resulting in welfare issues (e.g., body injury). Aggressive interactions can lead to a social hierarchy and influence the responses of animal behavior and physiology. However, the responses of fish behavior and physiology to social hierarchy is limited. This study examined the differences in the growth performance, aggression, cortisol level, brain serotonergic activity, and brain dopamine activity between the dominant individuals and the subordinate individuals in the short-term contest and in the long-term contest. Ultimately, our results suggest that subordinate hierarchy inhibits aggression but does not impact growth in black rockfish. The cortisol-related change in brain monoaminergic activity could be a potential indicator to predict aggressive behavior in black rockfish in captivity with an obvious social hierarchy. This study has provided new insight into the understanding of the regulatory mechanisms between social hierarchy and aggressive behavior in black rockfish, and contributed to building the theoretical basis for behavioral management to solve the welfare issues in captive fish. Aggressive interactions can lead to a social hierarchy and influence the responses of animal behavior and physiology. However, our understanding on the changes of fish behavior and physiology during the process of social hierarchical formation is limited. To explore the responses of fish behavior and physiology to social hierarchy, we examined the differences in the growth performance, aggression, cortisol level, brain serotonergic activity, and brain dopamine activity between the dominant individuals and the subordinate individuals of black rockfish (Sebastes schlegelii) in two time scenarios. In the short-term contest, the cortisol level and the ratio of telencephalic 5-hydroxyindoleacetic acid (5-HIAA)/5-hydroxytryptamine (5-HT) was significantly higher in subordinate individuals than in dominant individuals. In the long-term contest, the ratios of 5-HIAA/5-HT in all brain regions were significantly higher, and the frequency of aggressive acts were significantly lower in subordinate individuals than in dominant individuals. In contrast, no difference was detected in growth performance. Significant positive correlations between the cortisol level and serotonergic activity were observed in the short-term contest, but the serotonergic activity was negatively correlated with the aggressive behavior in the long-term contest. These results suggest that subordinate hierarchy inhibits aggression but does not impact growth in black rockfish. The cortisol-related change in brain monoaminergic activity could be a potential indicator to predict aggressive behavior in black rockfish in captivity with an obvious social hierarchy. [ABSTRACT FROM AUTHOR]

Simple Summary: Aggression after mixing has negative effects on growth performance and animal welfare in pigs. To analyze the temporal dynamics of social hierarchy formation and maintenance, a total of 102 weaned pigs (47 females and 55 barrows) were selected and blocked by sex and body weight. The pigs were mixed into 10 single-sex pens (10 to 11 pigs/pen) avoiding original littermates. Their behavior was recorded and observed for 72 h after mixing for the analysis of dominance hierarchy indices in each pen. The three hierarchical indices: I&SI, Elo rating, and Glicko rating, were associated with each other (|r| = 0.681~0.942, p < 0.001). I&SI was associated with the logarithms of frequency of active attack (|r| = 0.65, p < 0.05) and tended to be associated to logarithms of frequency of standoff (|r| = 0.48, p < 0.1). Elo rating, and Glicko rating were associated with logarithms of duration of being bullied (|r| = 0.393~0.401, p < 0.05). In addition, Glicko rating tended to be associated with the logarithms of duration of active attack and frequency of active attack (|r| = 0.416~0.439, p < 0.1). Multiple linear regression analyses of logarithms of dyadic behavior indicators for hierarchical indices indicated the same effects. The rank of pigs became stable earlier (p < 0.001) in females (23.06 ± 4.15 h post mixing) than in barrows (40.55 ± 4.71 h post mixing). The first ranked pig quickly appeared within a few hours after mixing and remained stable. Our study provided new insights into the re-establishment of social hierarchies in weaned pigs after mixing. Pigs are animals that live in groups and have social hierarchies within the group. After mixing, they can re-establish social hierarchies within several days through fighting. Dominance hierarchical indices, such as I&SI, Elo rating, and Glicko rating, have been used to analyze social hierarchies of some social animals but not pigs. I&SI index involves iterative calculations that first minimize the number of inconsistencies (I) in a dominance matrix, and then minimize the strength of those inconsistencies (SI). Elo rating and Glicko rating indices are based on the sequence in which interactions occur, and continuously update ratings by looking at interactions sequentially. To study the temporal dynamics of social hierarchy formation and maintenance in weaned pigs after mixing, a total of 102 pigs (47 females and 55 barrows) were selected by similar body weight and mixed in 10 pens (10 or 11 females or barrows per pen). Their behavior was recorded and observed for 72 h after mixing. Results showed that hierarchical indices I&SI, Elo rating, and Glicko rating were associated with each other (|r| = 0.681 ~ 0.942, p < 0.001). I&SI was associated with logarithms of frequency of active attack (|r| = 0.65, p < 0.05) and tended to associated with logarithms of frequency of standoff (|r| = 0.48, p < 0.1). Elo rating, and Glicko rating were associated with the logarithms of duration of being bullied (|r| = 0.393~0.401, p < 0.05). In addition, Glicko rating tended to be associated with the logarithms of duration of active attack and frequency of active attack (|r| = 0.416~0.439, p < 0.1). Multiple linear regression analyses of logarithms of dyadic behavior indicators for three hierarchical indices indicated the same effects. The time (hours) to achieve social stability of pigs after mixing was lower for females than barrows (23.06 ± 4.15 vs. 40.55 ± 4.71 h; p < 0.001). The most dominant pig (the first ranked) in each pen quickly appeared within a few hours after mixing and remained stable. Overall, our study demonstrated that the ranks calculated by the three dominance hierarchical indices: I&SI, Elo rating, and Glicko rating, were consistent and partially associated with part of the dyadic behavioral indicators in weaned pigs after mixing. [ABSTRACT FROM AUTHOR]