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.

Effect of milking environment enrichment through music on production performance and behaviour in cattle

Enrichment of milking environment through music has been proposed to help animals to cope with divergent stressors. In sight of the above, a study was conducted to evaluate the effect of Indian instrumental music-based environmental enrichment played in yaman raga on milk production performance and behaviour in cattle. A total of 21 lactating dairy cattle (Vrindavani crossbred cows) having similar parity and stage of lactation were selected in three groups - T1, T2 and T3, each consisting of seven animals. The T1 and T2 groups were exposed to instrumental flute and sitar, respectively, 10 min prior to the start of milking and continued till completion of milking; while the T3 group served as control. Musical enrichment of the environment was done using recorded-tape of flute and sitar was played in yamen raga at 40-60 (dB) decibel intensity. The results revealed a non-significant difference in milk yield, rectal temperature, respiration rate, T3 (triiodothyronine) and T4 (thyroxine) hormones. However, there exhibited a significant (p < 0.05) difference in milking time, milking speed, cortisol hormones and behavioural parameters such as milk let-down in the animals exposed to music compared to the control group. Thus, the results have significant implications relating to the behavioural fitness and welfare of dairy animals and reducing residual milk.

Music modulates emotional responses in growing pigs

There is a lack of clarity on whether pigs can emotionally respond to musical stimulation and whether that response is related to music structure. Qualitative Behavioral Assessment (QBA) was used to evaluate effects of 16 distinct musical pieces (in terms of harmonic structure) on emotional responses in nursery pigs (n = 30) during four periods: "habituation", "treatments", "breaks" and "final". Data were evaluated using Principal component analysis (PCA). Two principal components (PC) were considered in the analysis: PC1, characterized as a positive emotions index, included the emotional responses content, playful, sociable, and happy, whereas PC2, characterized as a negative emotions index, included fearful, inquisitive, and uneasy with positive loadings, and relaxed and calm with negative loadings. Musical stimulation (treatment) increased (P < 0.01) both emotional indices, compared to other periods and this response was influenced by harmonic characteristics of the music. We concluded that pigs have a wide variety of emotional responses, with different affective states related to the music structure used, providing evidence of its potential use as environmental enrichment for this species.

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.

Effects of long-term exposure to music on behaviour, immunity and performance of piglets

Context Music induces physiological responses in animals, and as an enriched environment, it may have a positive effect on behaviour and productivity. Aims This study aimed to determine the effects of different kinds of music on immunity, stress response and performance of piglets. Methods In total, 144 hybrid piglets (Yorkshire × Durac × Minpig) at the age of 7 weeks were divided into three treatment groups: slow-tempo string music (65 beats per min), fast-tempo wind music (200 beats per min), and control (i.e. no music). Exposure to music lasted for 42 days, from 8 to 14 weeks of age. During the experimental period, behavioural activities were observed, and physiological parameters, immune responses and growth performance were measured. Key results Results showed that long-term music exposure increased (P &lt; 0.01) playing and tail-wagging behaviours compared with the control group, but had no effect (P &gt; 0.05) on walking, lying, exploring, fighting or feeding behaviours. No effect (P &gt; 0.05) was found on the levels of growth hormone, salivary cortisol, serum cortisol, adrenocorticotrophic hormone, β-endorphin or dopamine, or on the performance of growing pigs. However, the specific music type slow-tempo string significantly (P &lt; 0.05) increased interleukin-4. Conclusions Long-term exposure to music does not affect stress response or growth performance in piglets. However, it promotes positive mood as indicated by increased playing and tail-wagging activities, and induces positive immunomodulation through increased interleukin-4 levels in piglets. Implications Exposure to music may be used to promote positive mood, and hence enhance welfare, in piglets.

Behavioural responses of piglets to different types of music

Music or other background sounds are often played in barns as environmental enrichment for animals on farms or to mask sudden disruptive noises. Previous studies looking at the effects of this practice on non-human animal well-being and productivity have found contradictory results. However, there is still a lack of discussion on whether piglets have the ability to distinguish different types of music. In this study, we exposed piglets to different music conditions to investigate whether the piglets preferred certain music types, in which case those types would have the potential to be used as environmental enrichment. In total, 30 piglets were tested for music type preference to determine whether growing pigs respond differently to different types of music. We used music from two families of instruments (S: string, W: wind) and with two tempos (S: slow, 65 beats/min (bpm); F: fast, 200 bpm), providing four music-type combinations (SS: string-slow; SF: string-fast; WS: wind-slow; WF: wind-fast). The piglets were given a choice between two chambers, one with no music and the other with one of the four types of music, and their behaviour was observed. The results showed that SS and WF music significantly increased residence time (P<0.01) compared with the other music conditions. Compared with the control group (with no music), the different music conditions led to different behavioural responses, where SS music significantly increased lying (P<0.01) and exploration behaviour (P<0.01); SF music significantly increased tail-wagging behaviour (P<0.01); WS music significantly increased exploration (P<0.01); and WF music significantly increased walking, lying, standing and exploration (all P<0.01). The results also showed that musical instruments and tempo had little effect on most of the behaviours. Fast-tempo music significantly increased walking (P=0.02), standing (P<0.01) and tail wagging (P=0.04) compared with slow-tempo music. In conclusion, the results of this experiment show that piglets are more sensitive to tempo than to musical instruments in their response to musical stimulation and seem to prefer SS and WF music to the other two types. The results also suggest a need for further research on the effect of music types on animals.

Effects of auditory and physical enrichment on 3 measurements of fear and stress (tonic immobility duration, heterophil to lymphocyte ratio, and fluctuating asymmetry) in several breeds of layer chicks

The purpose of this study was to analyze the effect of auditory enrichment (by means of classical music) or physical enrichment (by means of hanging colored string bunches and barley grains on the floor) on tonic immobility duration, heterophil to lymphocyte ratio, and fluctuating asymmetry (FA) in chicks of several layer breeds. In experiment 1, 192 chicks from 8 Spanish breeds and 1 White Leghorn population were reared in cages with or without music auditory enrichment until 8 wk of age. The effect of music auditory enrichment was significant for heterophil to lymphocyte ratio (P < 0.05). The ratios were higher in chicks reared without music than in those reared with music, suggesting that auditory enrichment from classical music reduces stress in chicks. There were significant differences in morphological trait measurements (relative asymmetry of wing length, leg width, and combined asymmetry; P < 0.05), being greater in chicks reared without music. This result suggests that FA is a good indicator for stress level in chicks, given that it follows the same trend as that found for heterophil to lymphocyte ratio. There was a significant treatment by breed interaction (P < 0.05) for tonic immobility duration, indicating no consistent effect by auditory enrichment on tonic immobility duration across breeds. In experiment 2, 180 chicks from 3 Spanish breeds were housed in pens with or without physical enrichment (colored plastic string bunches and barley grains on the floor) until 6 wk of age. The effect of physical enrichment on tonic immobility duration, heterophil to lymphocyte ratio, and FA was not significant, indicating no effect on fear and stress in layer chicks. In conclusion, auditory enrichment by means of classical music is a reliable method for reducing stress levels in several breeds of layer chicks. However, music auditory enrichment was not effective in reducing fearfulness in any of the layer breeds. Physical enrichment by means of colored plastic string bunches and floor barley grains does not appear to be an effective method for reducing stress and fear in layer chicks.

Toward a better understanding of pig behavior and pig welfare

Pork production began to flourish in the USA after the practice of finishing pigs on corn was popularized in the late 1600s. By the 1840s, there were 35 million pigs and 20 million people in the USA and Cincinnati was the world's largest pork market. Between 1890 and the present, the total number of pigs in the USA has remained at 50-60 million, but dramatic changes in swine husbandry over the course of the 20th century have metamorphosed pig production from small, extensive (outdoor), labor-dependent enterprises into large, intensive (indoor), capital-dependent, production systems. This development has led to debate concerning the impact of swine production on animal/human health, the environment, and the welfare of the animals under our care. In a very tangible way, the future of pork production depends on effectively addressing the public's concerns regarding animal welfare and health. Here, we review basic sensory and behavioral aspects of swine with the objective of reaching a better understanding of pig behavior and pig welfare. The premise of this discussion is that safeguarding animal welfare and health is good for pigs, pork producers and the animal-conscious public.

Common carp (Cyprinus carpio) response to two pieces of music ("Eine Kleine Nachtmusik" and "Romanza") combined with light intensity, using recirculating water system

The objective of this study was to further investigate the effects of music on fish physiology, bearing in mind available information regarding the involvement of endogenous and exogenous factors in fish farming. Therefore, Cyprinus carpio (50.5 +/- 0.36 g) were reared in a recirculating water system under 80 and 200 lux and subjected to no music at all (control, ambient noise only), 4 h of Mozart's "Eine Kleine Nachtmusik", or 4 h of anonymous "Romanza-Jeux Interdits" for 106 days. Both music treatments resulted in increased growth performance at both light intensities, with Romanza treatment at 200 lux resulting in better growth performance than Mozart treatment. Furthermore, feed efficiency for the Romanza groups was significantly better than for the control. Although no significant music effect was apparent for brain neurotransmitters, lower anterior intestine alkaline protease levels were detected for both music treatments. Taking into consideration the numerous advantages of recirculating water systems, it should be emphasised that fish response to music expresses the results of various physiological and biochemical processes, especially when fish notably respond differently when subjected to two different pieces of music.