Reliability of caretakers' ratings of captive bottlenose dolphins (Tursiops truncatus) and finless porpoises' (Neophocaena asiaeorientalis sp.) behavioral style for welfare monitoring

Qualitative ratings are increasingly used to assess animal welfare. We investigated the associations between daily caretakers' ratings of individuals' behavioral style, behavior during free time, participation during training sessions, and environmental variables in captive Yangtze finless porpoises, East-Asian finless porpoises, and bottlenose dolphins. Associations between caretakers' ratings and behavior were found, including social swimming, fast swimming, play, interaction with humans, and agonistic and socio-sexual interactions. Ratings were also associated with participation during training sessions and food intake. Social separation, transport to a new pool, high visitors' density, and holding of a sick conspecific were associated with ratings indicating a deteriorated human-animal relationship, a lower interest/fear of the environment, and/or a higher social cohesion depending on the group. Through principal component analyses, new variables that represented both caretakers' ratings and behavior and that could be used for an easier interpretation of the data for welfare monitoring within each group were extracted. Caretaker ratings and behavior should be used as a complement to previously validated indicators to detect changes in welfare state and understand the potential causes of these changes.

What drives horse success at following human-given cues? An investigation of handler familiarity and living conditions

Cues such as the human pointing gesture, gaze or proximity to an object are widely used in behavioural studies to evaluate animals' abilities to follow human-given cues. Many domestic mammals, such as horses, can follow human cues; however, factors influencing their responses are still unclear. We assessed the performance of 57 horses at a two-way choice task testing their ability to follow cues of either a familiar (N = 28) or an unfamiliar informant (N = 29). We investigated the effects of the length of the relationship between the horse and a familiar person (main caregiver), their social environment (living alone, in dyads, or in groups) and their physical environment (living in stalls/paddocks, alternating between paddocks and pastures, or living full time in pastures). We also controlled for the effects of horses' age and sex. Our results showed that horses' success rate at the task was not affected by the familiarity of the informant and did not improve with the relationship length with the familiar informant but did increase with the age of the horses. Horses living in groups had better success than the ones kept either in dyads or alone. Finally, horses housed in small paddocks had lower success than those living on pasture. These results indicate that with age, horses get better at following human-given indications regardless of who the human informant is and that an appropriate living and social environment could contribute to the development of socio-cognitive skills towards humans. Therefore, such aspects should be considered in studies evaluating animal behaviour.

Horses form cross-modal representations of adults and children

Recently, research on domestic mammals' sociocognitive skills toward humans has been prolific, allowing us to better understand the human-animal relationship. For example, horses have been shown to distinguish human beings on the basis of photographs and voices and to have cross-modal mental representations of individual humans and human emotions. This leads to questions such as the extent to which horses can differentiate human attributes such as age. Here, we tested whether horses discriminate human adults from children. In a cross-modal paradigm, we presented 31 female horses with two simultaneous muted videos of a child and an adult saying the same neutral sentence, accompanied by the sound of an adult's or child's voice speaking the sentence. The horses looked significantly longer at the videos that were incongruent with the heard voice than at the congruent videos. We conclude that horses can match adults' and children's faces and voices cross-modally. Moreover, their heart rates increased during children's vocalizations but not during adults'. This suggests that in addition to having mental representations of adults and children, horses have a stronger emotional response to children's voices than adults' voices.

Male mice and cows perceive human emotional chemosignals: a preliminary study

Olfactory cues of individuals of the same species or from different species may induce changes in behaviors and physiological reactions in mammals. However, there are few studies on the influence of human odor on animal behavior and welfare, especially those of rodents and farm animals. The present study aimed to investigate whether the odor of a stressed human (in sweat) would modify the behavior of mice and cows. We hypothesized that laboratory and farm animals can perceive human emotions though olfactory cues and that human emotional chemosignals can modify their behavioral reactions and welfare. Two odors of human axillary sweat were collected from engineering students (n = 25, 14 females and 11 males; 21.1 ± 0.7 years old, range: 19-23 years old): a "stress" odor collected after an exam and a "non-stress" odor collected after a standard class. Two experiments were then conducted to test the discrimination of these two odors by male mice (n = 20) under standard conditions and by cows (n = 10) under farm conditions. During the experiments, the behavioral responses of the animals to both odors (through a dispenser for the mice and a bucket for the cows) were observed. The mice produced significantly (p = 0.004) more fecal pellets with the stress odor dispenser than with the non-stress-odor dispenser. The cows spent significantly (p = 0.04) more time smelling the non-stress-odor bucket than control. For both species, the other behaviors observed did not differ significantly between the odors. Mice and cows seemed to perceive and react to stressful human chemosignals. Mice showed physiological reactions that indicated stress in response to the stress odor of humans, while cows showed preference reactions in response to the non-stress odor of humans. This preliminary study showed that laboratory and farm animals, such as male mice and cows, seemed to discriminate certain odors emitted by humans that were likely related to different emotions. Animals may recognize stressful human chemosignals, associate these signals with negative husbandry practices or human-animal relationships, and consequently modify their behavior.

Meat quality, skin damage and reproductive performance of ostriches exposed to extensive human presence and interactions at an early age

The effect human presence and interactions performed after hatch to 3 months of age has on ostrich meat quality, skin damage and reproductive performance at a later age was investigated in 416-day-old ostrich chicks. The chicks were allocated to one of the three treatments, which varied with regard to exposure to human presence and care for 3 months post-hatch: HP1-extensive human presence with physical contact (touch, stroking), gentle human voice and visual contact; HP2-extensive human presence with gentle human voice and visual contact without physical contact; S-standard control treatment, where human presence and visual contact were limited to routine management, feed and water supply only. Carcass attributes (carcass weight, dressing percentage and drumstick weight), meat quality traits (pH, colour and tenderness) and skin traits (skin size, skin grading and number of lesions) were evaluated on twenty-four 1-year-old South African Black (SAB) ostriches. Reproductive performance (egg production, average egg weight, number of clutches, clutch size, chick production, average chick weight, fertility and hatchability percentage) were recorded for the first three breeding seasons of 23 SAB pair-bred females from this study. No differences in carcass attributes, meat quality, skin traits and reproductive performance were found between treatments (P > 0.05). It was evident that exposure of day-old ostriches to extensive human presence and interaction as chicks did not influence carcass attributes, meat quality or skin traits at slaughter age, but more importantly, it did not compromise their reproductive performance.

Horses feel emotions when they watch positive and negative horse-human interactions in a video and transpose what they saw to real life

Animals can indirectly gather meaningful information about other individuals by eavesdropping on their third-party interactions. In particular, eavesdropping can be used to indirectly attribute a negative or positive valence to an individual and to adjust one's future behavior towards that individual. Few studies have focused on this ability in nonhuman animals, especially in nonprimate species. Here, we investigated this ability for the first time in domestic horses (Equus caballus) by projecting videos of positive and negative interactions between an unknown human experimenter (a "positive" experimenter or a "negative" experimenter) and an actor horse. The horses reacted emotionally while watching the videos, expressing behavioral (facial expressions and contact-seeking behavior) and physiological (heart rate) cues of positive emotions while watching the positive video and of negative emotions while watching the negative video. This result shows that the horses perceived the content of the videos and suggests an emotional contagion between the actor horse and the subjects. After the videos were projected, the horses took a choice test, facing the positive and negative experimenters in real life. The horses successfully used the interactions seen in the videos to discriminate between the experimenters. They touched the negative experimenter significantly more, which seems counterintuitive but can be interpreted as an appeasement attempt, based on the existing literature. This result suggests that horses can indirectly attribute a valence to a human experimenter by eavesdropping on a previous third-party interaction with a conspecific.

The perception of humans by piglets: recognition of familiar handlers and generalisation to unfamiliar humans

Humans are part of the environment of domestic animals and interact with them daily, providing a good basis for the study of interspecific relationships. Abilities to discriminate and recognise individuals form the basis of these relationships, and they are crucial skills for domestic animals, since individual humans can differ in their behaviour towards them. At the same time, with experience, animals may develop a general memory of humans and generalise their behaviour towards strangers. This study aimed to determine the extent to which weaned piglets can discriminate familiar humans and generalise their past experience when faced with unfamiliar humans. Forty-eight groups of three piglets were submitted to two consecutive 5-day conditioning periods of the same or opposite valence (positive and/or negative) given by one (A) or two (A then B) handlers. The reactivity of piglets to a motionless human and to an approaching human was measured before and after conditioning periods with unfamiliar and familiar handlers. Thereafter, piglets which received treatments with the two handlers A and B were subjected to a choice test between both handlers. The reactivity to an approaching human appeared to better reflect the past experience with familiar handlers since piglets clearly recognised them and adapted their behaviour accordingly. In contrast, reaction of piglets to a motionless human reflected their natural propensity to seek interaction, even after a negative experience. Although piglets were able to extend their memory of humans to an unfamiliar human through generalisation, many factors seemed to interact in this process, especially the complexity of the previous experience (inconsistent vs consistent) and the context in which piglets met the unfamiliar human (motionless vs approaching). We conclude that discrimination and generalisation processes of reactivity to humans do not simply rely on past interactions, but also depend on the context according to the degree of similitude with their past experience.