A method for measuring the aversiveness of sounds to domestic hens

Environmental Gradients and Hen Spatial Distribution in a Cage-Free Aviary System: Internet of Things-Based Real-Time Monitoring for Proactive Management

This study assessed environmental gradients at different heights in a multi-tiered aviary and their relationship with hen spatial distribution. Two pens of an experimental aviary housing 225 Novogen hens (Novogen S.A.S., Plédran, France) each were monitored when their hens were 32-52 weeks old over three periods (January, March, and June). The environmental conditions (humidity, sound intensity, NH3, CO2, and particulate matter; PM: PM1, PM2.5, PM4, and PM10) were continuously recorded every 10 min, 24 h per day, at three heights (floor and middle and upper tiers) using an IoT-based system. Hen distribution was analysed using video recordings from 04:00 to 20:00, scanning 15 min for every 30 min of video. On the whole, the air quality was always consistent with the recommended values for laying hens. The middle tier, where nests were located, exhibited a higher humidity and CO2 and PM concentration compared to the upper tier and floor, suggesting reduced airflow. This result can be related to the reduced length of the experimental barn containing only one row of equipment, which likely affected air circulation and distribution compared to what happens in commercial barns with several rows and a length over 50 m. Hen distribution varied during the day, with hen presence on the floor being highest in the midday (58% of hens) and correlated with increased particulate matter (r = 0.57-0.60; p < 0.001) and NH3 concentrations (r = 0.33; p < 0.001). Hens occupied the upper tier more in June (34% vs. 24% in January; p < 0.001), correlating with lower humidity and PM levels. Understanding daily and seasonal changes in environmental gradients at different aviary tiers could help optimise ventilation schemes and air quality control and ensure hen welfare, health, and production throughout the laying cycle.

Do Cockatiels Choose Their Favourite Tunes? Use of Touchscreen for Animal Welfare Enhancement and Insights into Musical Preferences

Music may be one of the oldest forms of art, and its appreciation is thought to be universal among humans. Music could also represent a useful tool to improve captive animals' welfare, especially if individuals can choose the music they prefer. The ability to discriminate between different kinds of music or composers has been demonstrated in numerous non-human species. However, a reinforcing effect of music was found in only a few species, particularly in vocal learner birds such as Passeriformes and Psittaciformes. In this study, we explored whether cockatiels could learn to use a touchscreen to choose between two different pieces of music: first between rock and roll and calm music, and then between consonant and dissonant music. Some birds showed individual preferences for either rock and roll or calm music, but no preferences were found for consonance or dissonance. These results are in line with the hypothesis that vocal learners would be sensitive to music. Our findings offer new prospects for the study of musicality in non-humans and its potential applications for promoting welfare in captive animals: interacting with a touchscreen would allow them to have some control over their environment and to choose their preferred type of music as a form of environmental enrichment.

Music and Emotions in Non-Human Animals from Biological and Comparative Perspectives

The effects of sound stimulation as a sensorial environmental enrichment for captive animals have been studied. When appropriately implemented for farm animals, it can improve welfare, health, and productivity. Furthermore, there are indications that music can induce positive emotions in non-human animals, similar to humans. Emotion is a functional state of the organism involving both physiological processes, mediated by neuroendocrine regulation, and changes in behavior, affecting various aspects, including contextual perception and welfare. As there is very limited information on non-human animals, the objective of this review is to highlight what is known about these processes from human biological and comparative perspectives and stimulate future research on using music to improve animal welfare.

Affective trajectories: Are hens influenced by positive and negative changes in their living conditions?

Most studies of the effects of housing and husbandry on animals' affective states and welfare investigate the impact of stable living conditions, comparing for example, animals living in enriched environments with those living in non-enriched ones. Changes in living conditions, including from more to less enriched environments, have also been found to have effects on measures of affective state and welfare in some species. But these studies have not investigated whether it is the trajectory of change that has affected the animals (e.g., worsening conditions), or simply the nature of their final environment (e.g., non-enriched). Here, we hypothesised that laying hens living in worsening conditions across a six-week period (gradually moving from preferred to non-preferred living conditions; "Trajectory to Non-Preferred", TNP, n = 30), would show evidence of more negative affective states and poorer welfare than those living continuously in non-preferred conditions for the same duration ("Stable Non-Preferred", SNP, n = 30). We also hypothesised that hens living in improving conditions (gradually moving from non-preferred to preferred living conditions; "Trajectory to Preferred", TP, n = 30), would show evidence of more positive affective states and better welfare than those living continuously in preferred conditions ("Stable Preferred", SP, n = 30). The preferred living condition provided extensive resources and intermittent rewarding events (such as the delivery of food treats) known to be valued and preferred by most hens, while the non-preferred living condition provided just basic resources and intermittent aversive events (e.g., loud noises). The hens' affective states and welfare were measured using home-pen behavioural observations, body condition assessments, physiological stress measures (e.g., blood corticosterone, glucose, etc.), physical challenge tests, and judgement bias tests. A number of differences between hens in the trajectory and stable living conditions were found: TP hens were lighter, showed more foraging behaviour and less standing alert and head-shaking than SP hens, while TNP hens showed more head-shaking, mild feather pecking and aggressive attacking of pen mates than SNP hens. However, some of these differences failed to reach significance following Benjamini adjustments for multiple testing. The groups also did not differ in their judgement biases (measured in a sub-sample of 12 hens per experimental group), response to physical challenges, or measures of physiological stress. We conclude that the hens in the present study showed some evidence of responsiveness to 'affective trajectories' in their living conditions, but no definitive effects on their affective states and welfare.

A scoping review of freight rail noise and vibration impacts on domestic animal health and welfare

Multiple benefits of freight rail activity have been shown for commercial agribusiness, yet the effects of freight rail-related noise and vibration on domestic livestock health and welfare has so far received little research attention. This scoping review examines peerreviewed and grey literature addressing associations between freight rail noise, vibration and impacts on domestic livestock. Six databases (Scopus, Science Direct, SAGE, TRID, SPARK, ARRB) were searched for relevant literature published from 1980–2019. PRISMA search procedures were used to identify 28 publications relevant to domestic livestock, as well as noise or vibration impact of rail applicable to the freight rail context. Included publications addressed a range of livestock and related species, covering descriptive, review, and experimental findings on noise and vibration impacts. Five publications addressed vibration effects, and 23 addressed noise effects. Effects of noise and vibration on different species indicated that adverse effects vary depending on exposure intensity. The literature indicates that specific thresholds for noise and vibration exposure should be considered when managing freight rail impacts on commercial agribusiness involving avian and mammalian species. Freight rail noise and vibration likely exceeds thresholds for discomfort and harm for avian and mammalian species. Future research should consider case studies that specifically focus on integrating freight rail noise and vibration data to derive species-specific guides for animal health and welfare purposes.

Animal Signals, Music and Emotional Well-Being

Playing music or natural sounds to animals in human care is thought to have beneficial effects. An analysis of published papers on the use of human-based music with animals demonstrates a variety of different results even within the same species. These mixed results suggest the value of tailoring music to the sensory systems of the species involved and in selecting musical structures that are likely to produce the desired effects. I provide a conceptual framework based on the combined knowledge of the natural communication system of a species coupled with musical structures known to differentially influence emotional states, e.g., calming an agitated animal versus stimulating a lethargic animal. This new concept of animal-based music, which is based on understanding animal communication, will lead to more consistent and specific effects of music. Knowledge and appropriate use of animal-based music are important in future research and applications if we are to improve the well-being of animals that are dependent upon human care for their survival.

Examining affective structure in chickens: valence, intensity, persistence and generalization measured using a Conditioned Place Preference Test

When measuring animals' valenced behavioural responses to stimuli, the Conditioned Place Preference (CPP) test goes a step further than many approach-based and avoidance-based tests by establishing whether a learned preference for, or aversion to, the location in which the stimulus was encountered can be generated. We designed a novel, four-chambered CPP test to extend the capability of the usual CPP paradigm to provide information on four key features of animals' affective responses: valence, scale, persistence and generalization. Using this test, we investigated the affective responses of domestic chickens (Gallus gallus domesticus) to four potentially aversive stimuli: 1. Puffs of air; 2. Sight of (robotic) snake; 3. Sprays of water; 4. Sound of conspecific alarm calls. We found conditioned avoidance of locations associated with the air puffs and water sprays (Friedman's χ2 (3) = 13.323 p > .005; χ2 (3) = 14.235 p > .005), but not with the snake and alarm calls. The scale of the learned avoidance was similar for the air puff and water spray stimuli, but persistence and generalization differed. We conclude that the four chambered CPP test can have a valuable role to play in making multi-feature measurements of stimulus-generated affective responses, and we highlight the value of such measurements for improving our understanding of the structure of affect in chickens and other animals.

Chopped or long roughage: what do calves prefer? Using cross point analysis of double demand functions

The present study aimed to quantify calves'(Bos taurus) preference for long versus chopped hay and straw, and hay versus straw, using cross point analysis of double demand functions, in a context where energy intake was not a limiting factor. Nine calves, fed milk replacer and concentrate, were trained to work for roughage rewards from two simultaneously available panels. The cost (number of muzzle presses) required on the panels varied in each session (left panel/right panel): 7/35, 14/28, 21/21, 28/14, 35/7. Demand functions were estimated from the proportion of rewards achieved on one panel relative to the total number of rewards achieved in one session. Cross points (cp) were calculated as the cost at which an equal number of rewards was achieved from both panels. The deviation of the cp from the midpoint (here 21) indicates the strength of the preference. Calves showed a preference for long versus chopped hay (cp  = 14.5; P  = 0.004), and for hay versus straw (cp  = 38.9; P = 0.004), both of which improve rumen function. Long hay may stimulate chewing more than chopped hay, and the preference for hay versus straw could be related to hedonic characteristics. No preference was found for chopped versus long straw (cp  = 20.8; P = 0.910). These results could be used to improve the welfare of calves in production systems; for example, in systems where calves are fed hay along with high energy concentrate, providing long hay instead of chopped could promote roughage intake, rumen development, and rumination.

Behavior analysis and farm animal welfare

This article demonstrates that there is a role for behavior-analytic techniques in the area of farm animal welfare and provides examples of the kinds of work that can be done. Behavior-analytic procedures, specifically those used in the study of psychophysics, preference, and demand, can provide answers to three questions people concerned with the welfare of farm animals are likely to ask: What can the animals detect? What do they like and dislike? What will they work to attain or preserve? Such information certainly is necessary for making reasonable decisions about animal welfare, although it is not sufficient in and of itself.

Effect of low light and high noise on behavioural activity, physiological indicators of stress and production in laying hens

1. Commercial laying hens are commonly housed in noisy and dim environments, yet relatively little is known about whether these conditions, particularly in combination, have any effect on welfare or egg production. 2. The study was designed to investigate whether chronic exposure to continuous noise (60 dB(A) vs. 80 dB(A)) and/or light intensity (150 lux vs. 5 lux) during the critical period of coming into lay (16-24 weeks of age) influenced behaviour (activity, resting and feather maintenance), physiological stress (plasma corticosterone and heterophil to lymphocyte ratio) and production (number and weight of eggs laid) in laying hens. 3. Hens in the low light pens were less active and preened and dust-bathed more than those housed in 150 lux; hens in the high noise pens rested more frequently than those in quieter pens. 4. There was no evidence that chronic exposure to low light or high noise caused appreciable physiological stress but egg production was affected by these conditions. Hens kept in pens with low light or high noise laid fewer eggs per day than those kept in high light or low noise pens. These effects were additive, so that the fewest eggs were laid by hens subject to both low light and high noise. 5. These results show that low light intensity and continual high background noise have a detrimental effect on egg production in the early laying phase as well as influencing the time allocated to different behaviours. However there was no strong evidence for a physiological stress response to either of these conditions or their combination.

Demand equations for qualitatively different foods under fixed-ratio schedules: a comparison of three data conversions

Concurrent schedules were used to establish 6 hens' preferences for three foods. The resulting biases suggested wheat was preferred over honey-puffed and puffed wheat, and puffed wheat was the least preferred food. The hens then responded under fixed-ratio schedules for each food in 40-min (excluding reinforcer time) sessions, with the response requirement doubling each session until no reinforcers were received. At the smaller ratios, the less preferred the food, the faster the hens' overall response rates (mainly as a result of shorter postreinforcement pauses) and the more reinforcers they received. The relations between the logarithms of the number of reinforcers obtained (consumption) and the response ratio (price) were well fitted by curvilinear demand functions. Wheat produced the smallest initial consumption (ln L), followed by honey-puffed and puffed wheat, respectively. The response requirement at which the demand functions predicted maximal responding (P(max)) were larger for wheat than for the other foods. Normalizing consumption and price, as suggested by Hursh and Winger (1995), moved the data for the three foods towards a single demand function; however, the P(max) values were generally largest for puffed wheat. The results of normalization, as suggested by Hursh and Silberberg (2008), depended on the k value used. The parameter k is related to the range of the data, and the same k value needs to be used for all data sets that are compared. A k value of 8.0 gave significantly higher essential values (smaller alpha values) for puffed wheat as compared to honey-puffed wheat and wheat, and the P(max) values, in normalized standard price units, were largest for puffed wheat. Normalizing demand by converting the puffed and honey-puffed wheat reinforcers to wheat equivalents (by applying the bias parameter from the concurrent-schedules procedure) maintained separate demand functions for the foods. Those for wheat had the smallest rates of change in elasticity (a) and, in contrast to the other analyses, the largest P(max) values. Normalizing demand in terms of concurrent-schedule preference appears to have some advantages and to merit further investigation.

Concurrent schedules: Quantifying the aversiveness of noise

Four hens worked under independent multiple concurrent variable-interval schedules with an overlaid aversive stimulus (sound of hens in a poultry shed at 100dBA) activated by the first peck on a key. The sound remained on until a response was made on the other key. The key that activated the sound in each component was varied over a series of conditions. When the sound was activated by the left (or right) key in one component, it was activated by the right (or left) key in the other component. Bias was examined under a range of different variable-interval schedules, and the applicability of the generalized matching law was examined. It was found that the hens' behavior was biased away from the sound independently of the schedule in effect and that this bias could be quantified using a modified version of the generalized matching law. Behavior during the changeover delays was not affected by the presence of the noise or by changes in reinforcement rate, even though the total response measures were. Insensitivity shown during the delay suggests that behavior after the changeover delay may be more appropriate as a measure of preference (or aversiveness) of stimuli than are overall behavior measures.

Discriminative and reinforcing stimulus properties of music for rats

We trained rats to discriminate music by Bach from that by Stravinsky using operant conditioning. The rats successfully learned the discrimination and transferred their discrimination to novel music by the same artists. Then, we trained rats on concurrent-chain schedule in which the terminal links were associated with different music, Bach or Stravinsky. The rats did not show strong preference for either style of music, although one subject showed a preference for Bach and another subject preferred Stravinsky. Finally, we examined the validity of the concurrent-chain procedure as a method of preference measurement with conspecific vocalization evoked by an aversive experience. Most of the rats preferred white noise to the conspecific vocalization. Therefore, music has a discriminative stimulus property but not a clear reinforcing property for rats.

Welfare aspects of the transport by road of sheep and pigs

That transport can be stressful to pigs and sheep has been inferred from behavioral and physiological measurements. Duration of journey is more likely to cause stress in pigs than in sheep, but loading and the start of travel are stressful to both. Vibration, related to vehicle design, and the jolting, shocks, and sudden impacts caused by road conditions and manner of driving, are probably of more importance than noise. Ventilation and stocking density can modulate the effects of ambient temperature, which may influence meat quality in pigs. Deprivation of food and water does not appear to stress sheep unduly, but this can become a serious welfare concern in the case of pigs. However, most journeys undertaken by pigs in the European Union are relatively short. In sheep, transport may follow soon after other stressful experiences such as weaning, shearing, handling, or marketing; the interaction of these factors in causing cumulative stress has not been studied. In pigs, fighting after the mixing of previously unacquainted animals is well known to be a welfare issue that can compromise meat quality. Considering the public interest in livestock transport and the large amounts of money involved, surprisingly little research has been done in the area, and more is urgently needed for legislation and welfare codes to be soundly based on scientific knowledge.

Punishment in human choice: direct or competitive suppression?

This investigation compared the predictions of two models describing the integration of reinforcement and punishment effects in operant choice. Deluty's (1976) competitive-suppression model (conceptually related to two-factor punishment theories) and de Villiers' (1980) direct-suppression model (conceptually related to one-factor punishment theories) have been tested previously in nonhumans but not at the individual level in humans. Mouse clicking by college students was maintained in a two-alternative concurrent schedule of variable-interval money reinforcement. Punishment consisted of variable-interval money losses. Experiment 1 verified that money loss was an effective punisher in this context. Experiment 2 consisted of qualitative model comparisons similar to those used in previous studies involving nonhumans. Following a no-punishment baseline, punishment was superimposed upon both response alternatives. Under schedule values for which the direct-suppression model, but not the competitive-suppression model, predicted distinct shifts from baseline performance, or vice versa, 12 of 14 individual-subject functions, generated by 7 subjects, supported the direct-suppression model. When the punishment models were converted to the form of the generalized matching law, least-squares linear regression fits for a direct-suppression model were superior to those of a competitive-suppression model for 6 of 7 subjects. In Experiment 3, a more thorough quantitative test of the modified models, fits for a direct-suppression model were superior in 11 of 13 cases. These results correspond well to those of investigations conducted with nonhumans and provide the first individual-subject evidence that a direct-suppression model, evaluated both qualitatively and quantitatively, describes human punishment better than a competitive-suppression model. We discuss implications for developing better punishment models and future investigations of punishment in human choice.

Behavioral evaluation of the psychological welfare and environmental requirements of agricultural research animals: theory, measurement, ethics, and practical implications

The welfare of agricultural research animals relies not only on measures of good health but also on the presence of positive emotional states and the absence of aversive or unpleasant subjective states such as fear, frustration, or association with pain. Although subjective states are not inherently observable, their interaction with motivational states can be measured through assessment of motivated behavior, which indicates the priority animals place on obtaining or avoiding specific environmental stimuli and thus allows conclusions regarding the impact of housing, husbandry, and experimental procedures on animal welfare. Preference tests and consumer demand models demonstrate that animal choices are particularly valuable when integrated with other behavioral and physiological measurements. Although descriptive assessments of apparently abnormal behavior such as stereotypies and "vacuum behaviors" provide indications of potentially impoverished environments, they should be used with some caution in drawing welfare conclusions. The development of stereotypies may in some cases be linked to psychiatric dysfunction and reflect underlying neurophysiological impairments, which have implications for the ability to perform flexible behavior and thus the quality of research data provided by this kind of behavioral measurement (e.g., in pharmaceutical research). Environmental modifications, commonly termed "enrichment," can have diverse consequences for cognitive function, physiological responses, health, psychological welfare, and research data. Simple practical modifications of housing, husbandry, and experimental design are suggested to improve the psychological welfare of agricultural research animals in accordance with the principles of refining, reducing, and replacing (the "3Rs"), which underlie US Public Health Service Policy, and prevailing public ethics.