In the current study, five novel avian β-defensins (AvBDs) were identified and characterized in tissues from Peking ducks (Anas platyrhynchos). The nucleotide sequences of these cDNAs comprised 198 bp, 182 bp, 201 bp, 204 bp, and 168 bp, and encoded 65, 60, 66, 67, and 55 amino acids, respectively. Homology, characterization and comparison of these genes with AvBD from other avian species confirmed that they were Apl_AvBD1, 3, 5, 6, and 16. Recombinant AvBDs were produced and purified by expressing these genes in Escherichia coli. In addition, peptides were synthesized according to the respective AvBD sequences. Investigation of the antibacterial activity of the Apl_AvBDs showed that all of them exhibited antibacterial activity against all 12 bacteria investigated (P<0.05 or P<0.01). In addition, the antibacterial activity of all of the AvBDs against M. tetragenus and P. multocida decreased significantly in the presence of 150 mM NaCl (P<0.01). None of the AvBDs showed hemolytic activity. Consistent with their broad-spectrum antibacterial activity, the five novel Apl_AvBDs inhibited replication of duck hepatitis virus (DHV) in vitro significantly (P<0.05). The mRNA expression of all five Apl_AvBD in most tissues, including immune organs and the liver, was upregulated in response to DHV infection at different time points. These findings provide evidence that these defensins activate the immune response to combat microbial infection.

Maternal deprivation (MD) in early life induces dysbiosis in the host gut microbiota, which is a key determinant of abnormal behavior in stress model individuals. Compared with the early parenting environment of the wild, captive giant pandas face frequent and premature maternal separation. Will this lead to imbalance in intestinal flora and stress in captive giant pandas? The purpose of this research is to evaluate the possible adverse effects of the traditional parenting mode on the gut microbiota of captive giant pandas. The results showed that the frequent and premature maternal separation at early stages of the young did not change α and β diversity indices of the gut microbes, but it increased the relative abundance of s_Clostridium_tetani and s_Clostridium_sp_MSJ_8 (significantly positively correlated with the metabolism of propionic acid) and also the concentrations of fecal metabolites that are related to stress (N-acetyl-l-aspartic acid and corticosterone) in the intestinal tract of giant pandas in adulthood. Thereby, the function of protein digestion and absorption in the intestines of captive giant pandas was decreased, and the metabolism of short-chain fatty acids was disturbed. In conclusion, the parenting experience of early maternal separation could adversely affect the stress caused by the unfavorable parenting environment in the early life of captive giant pandas related to the gut microbiota of the captive giant pandas in adulthood.

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 < 0.01) playing and tail-wagging behaviours compared with the control group, but had no effect (P > 0.05) on walking, lying, exploring, fighting or feeding behaviours. No effect (P > 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 < 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.