Environmental enrichment can improve animal welfare. As a method of environmental enrichment, the effect of different auditory stimulations on the behavior response and welfare of laying hen chicks has yet to be investigated. Therefore, this study was aimed at exploring the impact of various auditory exposures on the behavior, learning ability, and fear response of 4-week-old laying hen chicks. A total of 600 1-day-old chicks were randomly assigned to five different groups: C (control group), LM (Mozart’s String Quartets, 65 to 75 dB), LN (recorded ventilation fans and machinery, 65 to 75 dB), HN (recorded ventilation fans and machinery, 85 to 95 dB), and HM (Mozart’s String Quartets, 85 to 95 dB). The experiment was conducted from day 1 until the end of the experiment on day 28. Groups LM and LN were exposed to music and noise stimulation ranging from 65 to 75 dB. Groups HN and HM, meanwhile, received noise and music stimulation ranging from 85 to 95 dB. The control group (C) did not receive any additional auditory stimuli. During the experimental period, continuous behavioral recordings were made of each group of chicks from day 22 to day 28. On day 21, the PAL (one-trial passive avoidance learning) task was conducted. On days 23 and 24, OF (open field) and TI (tonic immobility) tests were performed, and the levels of serum CORT (corticosterone) and DA (dopamine) were measured. The results indicated that exposure to music and noise at intensities ranging from 85 to 95 dB could reduce comforting, preening, PAL avoidance rate, the total number of steps and grid crossings of OF, and the concentration of DA in 4 WOA chicks (p < 0.05), increase the freezing times of OF (p < 0.05); 65 to 75 dB of noise stimulation could reduce preening and total number steps of OF in 4 WOA chicks (p < 0.05), increase the freezing times of OF (p < 0.05); and 65 to 75 dB of music exposure could reduce the concentration of CORT in 4 WOA chicks (p < 0.05). Therefore, 65 to 75 dB of music exposure could produce positive effects on chicks and showed relatively low CORT level, whereas 85 to 95 dB of music and noise exposure could reduce comforting and preening behavior, impair learning ability, and increase the fear responses of chicks.

The purpose of this study was to investigate the effect of short-term stimulation of classical music on the behavior of pullets and to explore whether classical music as an auditory enrichment factor reduces the fear level in pullets. One hundred and twenty 10-weeks’old Roman white pullets were randomly divided into two treatments of which one group was exposed to classic music (M), and another one was the control group (N). The music was played during 8:00–18:00 every day for 7 consecutive days. The behavior of the focal animals was observed from 11:00 to13:00 every day for 7 days. The results showed that during the observation period, the pullets in group M had more comforting (P < .05) and preening (P < .05), but less aggressive (P < .01) and feather-pecking (P < .01) behaviors than those in group N. No significant difference was found in other behaviors and the duration of tonic immobility between the two groups. Therefore, auditory enrichment as a means of environmental enrichment can increase the welfare level of pullets to a certain extent.

The aim of this study was to investigate the effects of prolonged exposure to varying levels of music or noise on the behavioral, physiological, and immune responses of pullets following their transfer to an egg-laying facility. A total of 240 one-day-old Hy-Line Brown pullets were randomly assigned to five groups: 0 dB sound stimulation, low-decibel music (65-75 dB), high-decibel music (85-95 dB), low-decibel noise (65-75 dB), and high-decibel noise (85-95 dB) stimuli. Pullets received music or noise stimuli 10 h per d from 1-day-old to 16-wk-old and were then transferred to the egg-laying facility. The results indicated that feeding and drinking behaviors significantly decreased (P < 0.05), whereas feather pecking, aggression, and preening behaviors significantly increased (P < 0.05) in the pullets after transfer. Pullets also had higher serum cortisol (COR) levels (P < 0.05), whereas immunoglobulin Y (IgY), tumor necrosis factor-α (TNF-α), interferon-γ (INF-γ), interleukin-1β (IL-1β), interleukin-2 (IL-2) and interleukin-6 (IL-6) levels significantly increased (P < 0.05). Low-decibel sound stimuli increased aggressive behavior and decreased pecking behavior (P < 0.05). High-decibel sound stimuli decreased feather pecking, cage pecking, aggression, and sham dustbathing behaviors (P < 0.05). In addition, a low-decibel sound stimulus decreased the serum COR content, and increased the serum IL-6 level in the transferred pullets. A high-decibel sound stimulus also induced shorter tonic immobility (TI) durations in pullets on d 7 after transport stress. Meanwhile, high-decibel sound stimulus decreased the serum IL-6 and TNF-α levels of pullets. In conclusion, the transfer has detrimental effects on the pullets. Long-term sound stimulation effectively mitigated the negative impact of transportation stress on pullets. Among them, the high-decibel sound stimulus showed more promise in relieving transport stress.

Background: In contrast to the explosive increase of a population following biological invasion, natural dispersal, i.e., when a population disperses from its original range into a new range, is a passive process that is affected by resources, the environment, and other factors. Natural dispersal is also negatively impacted by genetic drift and the founder effect. Although the fates of naturally dispersed populations are unknown, they can adapt evolutionarily over time to the new environment. Can naturally dispersed populations evolve beneficial adaptive strategies to offset these negative effects to maintain their population in a stable state? Results: The current study addressed this question by focusing on the toad Bombina orientalis, the population of which underwent natural dispersal following the Last Glacial Maximum in Northeast Asia. Population genetic approaches were used to determine the genetic structure, dispersal pattern, and mating system of the population of B. orientalis in northeast China (Northern population). The results showed that this northern population of B. orientalis is a typical naturally dispersed population, in which the stable genetic structure and high level of genetic diversity of the population have been maintained through the long-distance biased dispersal behavior of males and the pattern of promiscuity within the population. Conclusions: Our findings suggest that naturally dispersed populations can evolve effective adaptive strategies to maintain a stable population. Different species may have different strategies. The relevance of these maintenance mechanisms for naturally dispersed populations provide a new perspective for further understanding the processes of speciation and evolution.

Objective: Early environmental enrichment in life can improve cognition in animals. The effect of prenatal auditory stimulation on learning ability and fear level in chick embryos remained unexplored. Therefore, this study investigated the effect of prenatal auditory stimulation on the learning ability and fear level of chicks.Methods: A total of 450 fertilized eggs were randomly divided into 5 groups, including control group (C), low-sound intensity music group (LM), low-sound intensity noise group (LN), high-sound intensity noise group (HN) and high-sound intensity music group (HM). From the 10th day of embryonic development until hatching, group LM and group LN received 65 to 75 dB of music and noise stimulation. Group HN and group HM received 85 to 95 dB of noise and music stimulation, and group C received no additional sound. At the end of incubation, the one-trial passive avoidance learning (PAL) task and tonic immobility (TI) tests were carried out, and the serum corticosterone (CORT) and serotonin (5-HT) concentrations were determined.Results: The results showed that compared with the group C, 65 to 75 dB of music and noise stimulation did not affect the PAL avoidance rate (p>0.05), duration of TI (p>0.05) and the concentration of CORT (p>0.05) and 5-HT (p>0.05) in chicks. However, 85 to 95 dB of music and noise stimulation could reduce duration of TI (p<0.05) and the concentration of CORT (p0.05) and PAL avoidance rate (p>0.05).Conclusion: Therefore, the prenatal auditory stimulation of 85 to 95 dB can effectively reduce the fear level of chicks while it does not affect the learning ability.

The evolutionary history of a species is generally affected by the combination of geological events and climate fluctuations. By analyzing the population features, genetic structure and the effective population historical dynamics of existing species, the population evolutionary history can be reestablished. In recent years, geological evidence shows that the Yilan–Yitong fault zone located in Northeast Asia experienced strong and frequent geological changes in the late Quaternary period. Species population history has been shaped by the combination of the complex climatic conditions of the Quaternary and Pleistocene glacial interglacial cycles and palaeogeological events in Northeast Asia and it has become a research focus for evolutionary biology researchers. In this study, mitochondrial and microsatellite molecular markers were used to reveal the population features, genetic structure, and the effective population historical dynamics of the Oriental fire‐bellied toad (Bombina orientalis). The results showed that the strong seismic activity of the Yilan–Yitong fault zone in the late Quaternary period was the main reason for the population differentiation of Oriental fire‐bellied toad in northeast China. The Quaternary Pleistocene glacial interglacial cycles led to the significant bottleneck effect of the western population located in the Maoer mountain area. As a result, the western population has low genetic diversity. Recent gene flow between eastern and western populations and historical evidence of population expansion proved that the dispersal behavior of the western populations was the main cause of the low genetic diversity and mitochondrial and nuclear discordance. Human economic activity may be the mainly driving factor. These evidences showed that the comprehensive influence of geology, climate, human activities and other factors should be considered in the process of exploring the evolutionary history of species.