Human-lamb bonding: oxytocin, cortisol and behavioural responses of lambs to human contacts and social separation

Brushing rams before and during electroejaculation improves sperm motility and kinetics with slight changes in stress biomarkers

The aim of this study was to determine whether brushing rams before and during electroejaculation (EE) reduces their stress response and improves the characteristics of the ejaculate. A single person brushed each ram for 5 min daily, for 15 days, in an individual pen. Semen was collected from five rams brushed before and during EE by the same brusher, while the other five were electroejaculated without being brushed. The treatments were exchanged three days later, so semen was collected from all the rams with both treatments. Brushing increased mass motility (P = 0.05), and curvilinear (P = 0.001), linear (P = 0.02), and average path (P = 0.01) velocities of sperm, as well as the average amplitude of lateral displacement of the sperm head (P = 0.05), and tended to increase sperm concentration (P = 0.09). Brushing tended to reduce the cortisol concentration (P = 0.06) and the duration of head movements when 2 V pulse series V was applied (P = 0.1). Brushing increased creatine kinase concentration (P = 0.04) and tended to increase rectal (P = 0.06) and maximum eye surface temperatures (P = 0.1), total time, and number of electrical pulses administered (P = 0.07 for both variables), as well as the sum of pulses per voltage applied during EE (P = 0.06). In rams accustomed to being brushed by the same person, brushing them before and during EE improved semen quality, with slight changes in the stress responses.

Effect of gentle physical contact on behavioural indicators in sheep

The available literature provides ample evidence for the importance of gentle treatment and handling of farm animals for the establishment of relationships with humans. The present study is an attempt to verify the assumption that massage can be a tool for building sheep-human relationships and to determine the impact of this technique on the behaviour of lambs. In total, 40 3-week-old lambs (20 ewes of the synthetic prolific-meat line (BCP) and 20 Świniarka breed ewes) were assigned to two control groups (BCP, Świniarka) and two experimental groups (BCP, Świniarka). The lambs from the experimental groups received modified Shantala massage. During each session, the zoophysiotherapists massaged the chest, forelimbs, abdomen, hindlimbs, back, and face always in the same way and the same order. The massage was applied three times a day (at fixed times) for 21 consecutive days. Based on the behaviour manifested by the lambs during the massage sessions, a 2-point scale was developed for assessment of the animals from the research groups. After the massage, behavioural tests with the participation of a human, a dog, and a novel object were carried out for three consecutive days. Behaviours indicating curiosity (frequency of interaction, time of direct contact, latency) and fear (frequency of climbing and attempts to escape, duration of vocalisation) were assessed. The behavioural tests revealed significant differences in the behaviour of massaged and non-massaged lambs of both breeds, which confirms that the massage has a modifying effect on the behaviour of these animals. The influence of the applied technique was reflected by an increase in curiosity and a reduced level of fear.

Novel 31-kHz calls emitted by female Lewis rats during social isolation and social inequality conditions

Whether commonly used experimental animals show aversion toward inequality of social rewards, as humans do remains unknown. We examined whether rats emitted the 22-kHz distress calls under social reward inequality. Rats showed affiliative behavior for a specific human who repeatedly stroked and tickled them. When experimenter stroked another rat in front of them and during social isolation, these rats emitted novel calls with acoustic characteristics different from those of calls emitted under physical stress, namely air-puff. Under inequality conditions, rats emitted calls with higher frequency (∼31 kHz) and shorter duration (<0.5 s) than those emitted when receiving air-puff. However, with an affiliative human in front of them, the number of novel calls was lower and rats emitted 50-kHz calls, indicative of the appetitive state. These results indicate that rats distinguish between conditions of social reward inequality and the presence of an experimenter, and emit novel 31-kHz calls.

Captive Blue-and-yellow macaws (Ara ararauna) show facial indicators of positive affect when reunited with their caregiver

In mammals, human-animal bonding is recognized as a source of positive affect for companion or farm animals. Because this remains unexplored in birds, we investigated captive parrots' perspective of the human-animal relationship. We used a classical separation-reunion paradigm and predicted that variations in parrots' facial displays and behaviours would indicate their appraisal of the relationship. The test was divided into three phases of two minutes each: the bird was placed in an unfamiliar environment with a familiar caregiver (union), then the bird was left alone (separation) and finally, the caregiver returned (reunion). The test was repeated 10 times for each bird and video recorded in order to analyze their behaviour. The data show significantly higher crown and nape feather heights, higher redness of the skin and higher frequency of contact-seeking behaviours during the union and reunion phases than during the separation phase during which they expressed long distance contact calls. We observed the expression of eye pinning during the union and reunion phases in one out of five macaws. We argue that variation in facial displays provides indicators of parrot's positive appraisal of the caretaker presence. Our results broaden the scope for further studies on parrots' expression of their subjective feelings.

Mother-young bond in non-human mammals: Neonatal communication pathways and neurobiological basis

Mother-young bonding is a process by which the young establish social preferences for their mother. It fosters reproductive success and the survival of offspring by providing food, heat, and maternal care. This process promotes the establishment of the mother-young bond through the interaction of olfactory, auditory, tactile, visual, and thermal stimuli. The neural integration of multimodal sensory stimuli and attachment is coordinated into motor responses. The sensory and neurobiological mechanisms involved in filial recognition in precocial and altricial mammals are summarized and analyzed in this review.

Positive Aspects of Welfare in Sheep: Current Debates and Future Opportunities

The concept of positive welfare is an expansion of the traditional understanding that animal welfare is defined by minimizing stress, pain, suffering, and disease. Positive welfare shifts the animal welfare narrative from a focus on reducing negative experiences to proactively providing animals with opportunities to have positive experiences and feelings. The concept, although around for several decades, is in its infancy in terms of developing ways of assessing positive welfare on farms, especially in extensive systems, and there are challenges in the adoption of positive welfare practices and the monitoring of continuous improvement at the farm level. Using an iterative approach, this critical review aims to explore the extent to which positive welfare interventions and indicators are positioned and have been developed within the animal welfare literature for sheep. This paper critiques existing positive welfare indicators, such as choices in food and the physical environment, conspecific social synchronization, maternal bonds, intergenerational knowledge transfer, positive human-animal relationships, etc., as currently assessed by the 'good life framework'. It also reviews the characteristics of scientific measures for (positive) affective states in the current sheep literature and their potential contribution to understanding positive welfare states in sheep. In conclusion, this paper provides recommendations for future research regarding sheep welfare.

Robot touch with speech boosts positive emotions

A gentle touch is an essential part of human interaction that produces a positive care effect. Previously, robotics studies have shown that robots can reproduce a gentle touch that elicits similar, positive emotional responses in humans. However, whether the positive emotional effects of a robot's touch combined with speech can be enhanced using a multimodal approach remains unclear. This study supports the hypothesis that a multimodal interaction combining gentle touch and speech by a robot enhances positive emotional responses. Here, we conducted an experiment using a robotic arm to perform a gentle touch combined with speech and compared three conditions: touch alone, speech alone, and touch with speech. We assessed participants' subjective ratings of valence, arousal, and human likeliness using subjective emotional responses. Furthermore, we recorded facial electromyography (EMG) from the corrugator supercilii and zygomaticus major muscles and measured skin conductance levels (SCLs) as physiological emotional responses. Our results show that touch combined with speech elicited higher subjective valence and arousal ratings, stronger zygomaticus major EMG and SCL activities than touch alone. The results suggest that the positive emotional effects of robotic touch can be boosted by combining elements of speech.

Stress during first gestation of ewes impairs memory and learning of male offspring

This study aimed to investigate the influence of gestational stress induced by lipopolysaccharide (LPS, Escherichia coli) on the physiological changes of ewes, as well as on the subsequent behavioral interaction between ewes and lambs and on the memory and learning of 30-day-old offspring in a T-maze. Thirty-six nulliparous pregnant crossbred Santa Ines ewes with an initial live weight of 45 ± 6 kg, age of 12 ± 2 months, and body condition score between 3 and 3.5 (on a scale of 1 to 5) were divided into two treatments: LPS treatment (E. coli; 0.8 μg.kg^-1) and Control (placebo/saline) administered in late pregnancy (day 120). Blood samples were collected before (0 h at 5:00 h) and 1 h, 2 h, 4 h, 8 h, 12 h, 24 h after the administration of LPS or placebo to determine the cortisol release curve. Rectal temperature was measured at the same time points. After birth, male lambs (N = 19) were used to evaluate the maternal-offspring behavioral interaction, weight, and cognitive ability in a T-maze. Blood cortisol and rectal temperature of ewes increased after LPS administration and returned to baseline levels after 24 h. The activities facilitating and stimulating suckling were higher on LPS group (P < 0.05). Lambs whose mothers were challenged with LPS during late pregnancy showed greater learning and memory disabilities including fear behavior and the inability to make decisions at 30 days of age in the T-maze. In sheep, the immunological stress induced by LPS in late pregnancy promotes an inflammatory response characterized by specific rectal temperature and cortisol release profiles, improving maternal care that can increase offspring survival; however, the exposure of sheep fetuses to maternal inflammation causes cognitive impairment in lambs at 30 days of age, which could not be reduced by the behavioral interaction between the mother and offspring.

Post-weaning stroking stimuli induce affiliative behavior toward humans and influence brain activity in female rats

Gentle touch contributes to affiliative interactions. We investigated the effects of gentle stroking in female rats on the development of affiliative behaviors toward humans and we exploratively examined brain regions in which activity was influenced by stroking. Rats that had received stroking stimuli repeatedly after weaning emitted 50-kHz calls, an index of positive emotion, and showed affiliative behaviors toward the experimenter. Hypothalamic paraventricular oxytocin neurons were activated in the rats after stroking. The septohypothalamic nucleus (SHy) in the post-weaningly stroked rats showed decreased activity in response to stroking stimuli compared with that in the non-stroked control group. There were negative correlations of neural activity in hypothalamic regions including the SHy with the number of 50-kHz calls. These findings revealed that post-weaning stroking induces an affiliative relationship between female rats and humans, possibly via activation of oxytocin neurons and suppression of the activity of hypothalamic neurons.

The effect of daily calf stroking frequency during the postnatal period on the establishment of the human-calf relationship

OBJECTIVE

Stroking calves during the postnatal period could effectively improve humancalf relationships. The objective of this study is to examine how daily calf stroking frequency during the postnatal period affects the establishment of human-calf relationships.

METHODS

Six calves were stroked by a trainer for 6 minutes once daily for 5 days after birth (D1). Six calves were stroked by a trainer for 3 minutes twice daily for 5 days after birth (D2). A further four calves were stared at but not stroked as the control group. The overall stroking or staring duration was the same for all groups, at 6 min/d and 30 min over 5 days. The tests for reactions to the stationary trainer in an unfamiliar environment and avoidance distance measurements for an approaching trainer were conducted at 1 month and 3 months after the treatment.

RESULTS

Calves in both stroking groups approached significantly closer to the stationary trainer, vocalized less, and looked at the trainer shorter than the control group at 1 month. However, at 3 months, there was no significant difference between the D1 and the control group, whereas the D2 approached significantly closer to the trainer and vocalized less, and looked at the trainer for a shorter time than the control group. For the avoidance distance, the trainer could approach closer to both stroking groups than the control at 1 month, however, there was no difference among groups at 3 months.

CONCLUSION

Our results suggested that the difference in the calf stroking procedure affected the established human-calf relationships, even though the total stroking duration was the same for all stroked calves. It is likely to be more effective to stroke more frequently than intensively when the aim is to establish better human-calf relationships within limited labor time.

Intranasal oxytocin affects the stress response to social isolation in sheep

Oxytocin (OT) is a neuropeptide hormone that modulates several social behaviors and can affect the anxiety and stress response. The aim of this study was to determine if administration of intranasal OT affects the stress response to social isolation in sheep. Twenty adult Merino ewes were assigned to two groups; 1) Control group (CG, n = 10), which received an intranasal administration of isotonic saline and 2) Oxytocin-treated group (OTG, n = 10), which received an intranasal administration of OT (24 IU) 40 min before the animals were placed in the social isolation test. During the social isolation test (10 min), the behavior of the sheep was recorded, and blood samples were obtained before and after the test for the determination of cortisol, glucose and serum proteins, and heart rate and surface temperature were recorded. The OTG ewes had a higher cortisol concentration (P = 0.04) after social isolation, tended to vocalize more (P = 0.06) during isolation, and tended to have lower globulin concentrations (P = 0.10) than the CG ewes. Contrary to what we expected, the administration of intranasal OT increased the stress response to social isolation in ewes, which was evidenced by endocrine (greater increase in cortisol concentration), physiological (a tendency to present lower concentration of globulins in blood) and behavioral (a tendency to vocalize more) indicators. This study suggests that the administration of intranasal OT increased the stress response to isolation possibly by strengthening the social bond among ewes.

The Power of a Positive Human-Animal Relationship for Animal Welfare

Domestic animals often seek and enjoy interacting with humans. Positive human-animal relationships can elicit positive emotions and other positive welfare outcomes. Nevertheless, our understanding of the underlying processes that govern the positive perception of humans by animals is incomplete. We cover the potential mechanisms involved in the development and maintenance of positive human-animal relationships from the perspective of the animal. This encompasses habituation, associative learning, and possibly attachment or bonding based on communication and social cognition. We review the indicators from the literature to assess a positive human-animal relationship. We operationally define this positive relationship as the animal showing voluntary approach and spatial proximity (seeking) and signs of anticipation, pleasure, relaxation, or other indicators of a rewarding experience from interacting with the human. For research, we recommend accounting for the baseline human-animal relationship in the animal's everyday life, and incorporating a control treatment rather than only comparing positive to negative interaction treatments. Furthermore, animal characteristics, such as previous experience, genetics, and individual predisposition, as well as contextual characteristics related to the social and physical environment, may modulate the perception of humans by animals. The human-animal relationship is also influenced by human characteristics, such as the person's familiarity to the animal, attitudes, skills, and knowledge. We highlight implications for current practices and suggest simple solutions, such as paying attention to the animal's behavioral response to humans and providing choice and control to the animal in terms of when and how to interact with humans. Practical applications to achieve a positive perception of humans could be better utilized, such as by incorporating training principles, while keeping in mind trust and safety of both partners. Overall, there is growing evidence in the scientific literature that a positive human-animal relationship can bring intrinsic rewards to the animals and thereby benefit animal welfare. Further research is needed on the underlying processes to establish an effective positive human-animal relationship, especially in regard to the type, frequency, and length of human interaction necessary. In particular, the importance of providing animals with a sense of agency over their interactions with humans remains poorly understood.

Where Do We Stand in the Domestic Dog ( Canis familiaris ) Positive-Emotion Assessment: A State-of-the-Art Review and Future Directions

Although there have been a growing number of studies focusing on dog welfare, the research field concerning dog positive-emotion assessment remains mostly unexplored. This paper aims to provide a state-of-the-art review and summary of the scattered and disperse research on dog positive-emotion assessment. The review notably details the current advancement in dog positive-emotion research, what approaches, measures, methods, and techniques have been implemented so far in emotion perception, processing, and response assessment. Moreover, we propose possible future research directions for short-term emotion as well as longer-term emotional states assessment in dogs. The review ends by identifying and addressing some methodological limitations and by pointing out further methodological research needs.

Gentle stroking stimuli induce affiliative responsiveness to humans in male rats

Gentle tactile stimuli have been shown to play an important role in the establishment and maintenance of affiliative social interactions. Oxytocin has also been shown to have similar actions. We investigated the effects of gentle stroking on affiliative relationships between humans and rats and the effects of gentle stroking on activation of oxytocin neurons. Male rats received 5-min stroking stimuli from an experimenter every other day for 4 weeks between 3 and 6 weeks of age (S3–6 group), for 4 weeks between 7 and 10 weeks of age (S7–10 group), or for 8 weeks between 3 and 10 weeks of age (S3–10 group). Control rats did not receive stroking stimuli. Rats in the S7–10 and S3–10 groups emitted 50-kHz calls, an index of positive emotion, more frequently during stroking stimuli. Rats in the S3–6, S7–10, and S3–10 groups showed affiliative behaviors toward the experimenter. Oxytocin neurons in the hypothalamic paraventricular nucleus of rats in the S3–6, S7–10, and S3–10 groups were activated following stroking stimuli. These findings revealed that post-weaning repeated stroking stimuli induce an affiliative relationship between rats and humans and activation of oxytocin neurons.

Effects of Stroking on Salivary Oxytocin and Cortisol in Guide Dogs: Preliminary Results

This pilot study aimed at investigating how salivary oxytocin levels are affected by human interaction and isolation in eight guide dogs (six Labrador retrievers and two golden retrievers; four males and four females, 21.87 ± 1.36 months old) just before assignment to the blind person. Each dog engaged, at one-week intervals, in a positive (5 min of affiliative interaction with their trainer) and a negative (5 min of isolation) condition. Saliva samples used for Enzyme Immunoassay (EIA) quantification of salivary oxytocin were collected before and immediately after both experimental conditions. In order to assess potential hypothalamic pituitary adrenal (HPA) axis activation that could have affected oxytocin levels, saliva samples were collected 15 min after both experimental conditions for EIA quantification of salivary cortisol and a behavioral assessment was performed during the negative condition. The results were compared using the Wilcoxon test (p < 0.05). Oxytocin concentrations showed a statistically significant increase after the positive interaction (p = 0.036) and no difference after the negative one (p = 0.779). Moreover, no difference (p = 0.263) was found between the cortisol concentrations after each experimental condition and no signs of distress were observed during the isolation phase. These preliminary findings support the hypothesis that stroking dogs has positive effects on their emotional state independently of hypothalamic pituitary adrenal axis activation.

Tactile stimulation reduces aggressiveness but does not lower stress in a territorial fish

Body tactile stimulation has a positive effect upon highly social animals, such as mammals and cleaner-client coral-reef fish, by relieving stress and improving health. Conversely, some tactile contacts are naturally detrimental, such as those resulted from aggressive interactions. To study whether positive responses from tactile stimulation are generalized among vertebrates, we tested its effect on stress response and aggressive behavior in a territorial fish species, Nile tilapia. We developed an apparatus made of a row of sticks bordered by silicone bristles that was positioned in the middle of the aquarium, and through which fish had to pass to access food, thus receiving tactile stimulation. Isolated fish experienced tactile stimulation for 7 days, and  were assigned to 2 types of stressors: non-social (confinement) or social (aggressive interaction). Each of them had a corresponding control treatment without tactile stimulation. Although fish spontaneously crossed the apparatus, we did not observe a decrease in plasma cortisol levels immediately after stressor application as a response to the use of the apparatus, either for social or non-social treatment. However, tactile stimulation reduced aggressive interaction in the social treatment, showing a positive effect on a territorial fish species, and pointing to a way to improve welfare.

Facial expression and oxytocin as possible markers of positive emotions in horses

Behavioural and physiological markers of discrete positive emotions remain little investigated in animals. To characterise new markers in horses, we used tactile stimulations to induce emotional situation of contrasting valence. In the Gentle grooming group (G, N = 13) horses were gently groomed during 11 sessions on the body areas they appreciated the most. Horses in the Standard grooming group (S, N = 14) were groomed using a fixed procedure, reported to induce avoidance reactions in some horses. At session 11, G horses expressed significantly more contact-seeking behaviours than S horses, which expressed significantly more avoidance behaviours. This result suggests positive emotions in G horses and negative emotions in S horses. Blood cortisol, oxytocin, heart rate and heart rate variability never differed between before and after the grooming session. However, after the 11 sessions, basal oxytocin levels were lower in the G than in the S group. This difference was unexpected, but supports studies showing that a low level of basal oxytocin could be a marker of better well-being. Analyses of facial expressions during grooming revealed significant differences between groups. These expressions appear to be more sensitive than behavioural indicators because they alone enabled differentiating emotions according to the group when horses were re-exposed to neutral grooming one year after the treatment.

Validation of a Commercially Available Enzyme ImmunoAssay for the Determination of Oxytocin in Plasma Samples from Seven Domestic Animal Species

The neurohormone oxytocin (OT) has a broad range of behavioral effects in mammals. It modulates a multitude of social behaviors, e.g., affiliative and sexual interactions. Consequently, the OT role in various animal species is increasingly explored. However, several issues have been raised regarding the peripheral OT measurement. Indeed, various methods have been described, leading to assay discrepancies and inconsistent results. This highlights the need for a recognized and reliable method to measure peripheral OT. Our aim was to validate a method combining a pre-extraction step, previously demonstrated as essential by several authors, and a commercially available enzyme immunoassay (EIA) for OT measurement, using plasma from seven domestic species (cat, dog, horse, cow, pig, sheep, and goat). The Oxytocin EIA kit (EnzoLifeSciences) was used to assay the solid-phase extracted samples following the manufacturer's instructions with slight modifications. For all species except dogs and cats, concentration factors were applied to work above the kit's sensitivity (15 pg/ml). To validate the method, the following performance characteristics were evaluated using Validation Samples (VS) at various concentrations in each species: extraction efficiency via spiking tests and intra- and inter-assay precision, allowing for the calculation of total errors. Parallelism studies to assess matrix effects could not be performed because of too low basal concentrations. Quantification ranges and associated precision profiles were established to account for the various OT plasma concentrations in each species. According to guidelines for bioanalytical validation of immunoassays, the measurements were sufficiently precise and accurate in each species to achieve a total error ≤30% in each VS sample. In each species, the inter-assay precision after 3 runs was acceptable, except in low concentration samples. The linearity under dilution of dogs and cats' samples was verified. Although matrix effects assessments are lacking, our results indicate that OT plasma levels can reliably be measured in several domestic animal species by the method described here. Studies involving samples with low OT plasma concentrations should pay attention to reproducibility issues. This work opens new perspectives to reliably study peripheral OT in a substantial number of domestic animal species in various behavioral contexts.

Oxytocin as an Indicator of Psychological and Social Well-Being in Domesticated Animals: A Critical Review

Oxytocin is often portrayed as a hormone specific to social behavior, reflective of positive welfare states, and linked to mental states. Research on oxytocin in domesticated animal species has been few to date but is rapidly increasing (in dog, pig, cattle, sheep), with direct implications for animal welfare. This review evaluates the evidence for the specificity of oxytocin as an indicator of: 1. Social, 2. Positive, and 3. Psychological well-being. Oxytocin has most often been studied in socially relevant paradigms, with a lack of non-social control paradigms. Oxytocin research appears biased toward investigating positive valence, with a lack of control in valence or arousal. Oxytocin actions are modulated by the environmental and social contexts, which are important factors to consider. Limited evidence supports that oxytocin's actions are linked to psychological states; nevertheless whether this is a direct effect of oxytocin per se remains to be demonstrated. Overall, it is premature to judge oxytocin's potential as an animal welfare indicator given the few and discrepant findings and a lack of standardization in methodology. We cover potential causes for discrepancies and suggest solutions through appropriate methodological design, oxytocin sampling or delivery, analysis and reporting. Of particular interest, the oxytocinergic system as a whole remains poorly understood. Appreciation for the differences that social contact and group living pose in domesticated species and the way they interact with humans should be key considerations in using oxytocin as a psychosocial indicator of well-being.

Behavioral evidence of heterospecific bonding between the lamb and the human caregiver and mapping of associated brain network

While behavioral mechanisms of bonding between young mammals and humans have been explored, brain structures involved in the establishment of such processes are still unknown. The aim of the study was to identify brain regions activated by the presence of the caregiver. Since human positive interaction plays an important role in the bonding process, activation of specific brain structures by stroking was also examined. Twenty-four female lambs reared in groups of three were fed and stroked daily by a female caregiver between birth and 5-7 weeks of age. At 4 weeks, an isolation-reunion-separation test and a choice test revealed that lambs developed a strong bond with their caregiver. At 5-7 weeks of age, lambs were socially isolated for 90min. They either remained isolated or met their caregiver who stroked them, or not, at regular intervals over a 90-min period. Neuronal activation was investigated at the end of the period for maximum c-Fos expression. Reunion with the caregiver appeased similarly the lambs whether stroking was provided or not. Stroking did not activate a specific brain network compared to no stroking. In both cases, brain regions associated with olfactory, visual and tactile cue processing were activated in the presence of the caregiver, suggesting a multisensory process involved. In addition, activation of the oxytocinergic system in the hypothalamic paraventricular nucleus induced by the presence of the caregiver suggests similar neuroendocrine mechanisms involved in inter-conspecific and animal-human bonding.

Effects of positive and negative human contacts and intranasal oxytocin on cerebrospinal fluid oxytocin

Despite the popularity of oxytocin (OT) research for its role in social behavior, the relationship between the social environment and endogenous central OT remains poorly understood. This study investigated the effects of positive and negative human contacts and intranasal OT administration on OT concentration in the cerebrospinal fluid (CSF). The pig was used as a model, with repeated CSF sampling through a spinal catheter using a within-subject design. Positive human contact led to sustained CSF OT elevation in pigs over 120min which outlasted the 15min interaction. Furthermore, the frequency of positive interactions was correlated with CSF OT increase. This provides a neurophysiological basis to positive human-animal relationships, with OT preserving bonds within but also between species through interactions. Conversely, CSF OT concentration did not vary during or after negative contact with an unfamiliar person, supporting CSF OT as a biomarker of positive valence in the human-animal relationship context. Intranasal OT administration resulted in peak CSF OT within 10min, with approximately 0.001% of the administered dose reaching the CSF. The sensitivity of the oxytocinergic system to variations in the social environment is a worthy area of investigation for its scientific and clinical implications. In particular, positive interactions result in outlasting central OT release.

Do lambs perceive regular human stroking as pleasant? Behavior and heart rate variability analyses

Stroking by humans is beneficial to the human-animal relationship and improves welfare in many species that express intraspecific allogrooming, but very few studies have looked at species like sheep that do not express such contact except around parturition. This study investigated the way lambs perceive regular human tactile contact using behavioral and physiological responses. Twenty-four lambs were reared and bucket-fed in groups of four. All were stroked daily by their familiar caregiver. At 8 weeks of age, the lambs were individually tested in their home pen but in a 1×1m open-barred pen after a 15h period of habituation to physical separation from peers while remaining in visual and auditory contact. Half of the lambs received stroking by their caregiver for 8min and half were exposed to their caregiver’s immobile presence. Heart rate and heart rate variability were recorded and analyzed by 2-min slots over the same interval based on three measures: mean heart rate value (HR), root mean square of successive differences (RMSSD) and standard deviation of all intervals measured between consecutive sinus beats (SDNN). Behavioral responses (ear postures of the lamb and time spent in contact with the familiar caregiver, on the knees of the familiar caregiver, and moving) were recorded throughout the test. Lamb HR decreased continuously while in the presence of their caregiver. Lambs being stroked showed slower HR and higher RMSSD which reflected positive emotional states compared to lambs left unstroked. All behavioral variables were highly correlated with the main component axis of the PCA analyses: the more the animals stayed in contact with their caregiver, the less they moved and the more their ears were hanging. This first component clearly differentiates lambs being stroked or not. Behavioral and physiological observations support the hypothesis that gentle physical contact with the caregiver is perceived positively by lambs.

Effect of supplementary milk feeding on growth and survival of Santa Inês lambs

The objective of this experiment was to evaluate the effect of alternative methods of feeding on the performance and mortality rate of suckling lambs. Eighty-four Santa Inês lambs, twins and singles, half male and half female, were used. The animals were divided into three groups: A (control), B (bovine milk) and C (bovine milk plus Multi-mixture). The experiment began when lambs were three weeks old and finished at weaning at 2 months of age. Each animal from group B received 200 mL of bovine milk daily; group C received 200 mL of bovine milk plus 20g of Multi-mixture daily. Weaning Weight (WW) was 10.90, 13.20 and 13.59 kg, respectively for groups A, B and C. Daily Weight Gain (DWG) was 126, 163 and 168 g.day-1 respectively. The mortality rate was higher (p<0.05) in group A than in group B and C. Gender influenced significantly (p<0.05) the DWG and WW. DWG and WW were lower for the animals that died compared to the animals that survived: 7.94 kg against 13.51 kg (WW) and 77 g against 165 g (DWG) respectively. The twins had lower (P<0.05) WW and DWG when compared to the singles. The use of milk-replacers with or without Multi-mixture is effective and it can increase the productivity of the system.

Possible involvement of oxytocin in modulating the stress response in lactating dairy cows

Oxytocin can attenuate the physiological and behavioral response to stress in animals. In this study we investigated the relationship between plasma oxytocin concentrations and the behavioral and physiological response of dairy cows to a repeated psychological stressor (novel environment). Twenty lactating multi-parous dairy cows were milked in a familiar milking parlor and in a novel environment. Blood samples were collected before and after milking in the familiar parlor (baseline) and on the second and fifth day in the novel parlor to measure plasma cortisol and oxytocin concentrations. Heart rate was recorded on all cows during milking in the familiar and novel environment. On all test days, the behavioral response of cows to milk cluster attachment was scored. On day 2 in the novel parlor, the oxytocin response, cortisol concentrations and heart rate were greater, and heart rate variability was lower than baseline values recorded in the familiar parlor. The results from this study suggest that oxytocin release is increased in response to exposure to a psychological stressor (novel environment) and that cows adapt to this stressor over time. After initial suppression, oxytocin levels increased over days of milking in a novel environment, whereas indicators of stress simultaneously decreased. Furthermore, the oxytocin increase was associated with habituation of the cortisol response in anticipation of milking in a novel environment, suggesting that oxytocin may be involved in habituation to a novel environment in dairy cows. This mechanism of habituation to novel environments may reflect an association between oxytocin and a "familiarization-habituation response" to repeated exposure to an initially novel environment that has previously been reported in humans.