Effects of prenatal auditory stimulation on physiological stress and neurotransmitter levels in developing embryos and day-old ducklings.

The objective of the study was to determine the effects of prenatal auditory stimulation (PAS) on serum levels of heat shock protein 70 (HSP70), ceruloplasmin (CPN), alpha-1acid-glycoprotein (AGP), corticosterone (CORT), ovotransferrin (OVT), and dopamine (DA) in duck embryos and hatchlings. Fertilised Khaki Campbell duck eggs were subjected to the following auditory stimulation treatments: 1) no additional sound treatment other than the background sound of the incubator's compressors at 40 dB (CONTROL), 2) exposure to pre-recorded traffic noise at 90 dB (NOISE), and 3) exposure to Mozart's Sonata for Two Pianos in D Major, K 488 at 90 dB (MUSIC). The NOISE and MUSIC treatments were for 20 min/h for 24 h (a total of 8 h/d), starting from embryonic days (ED) 13 to hatching. Prenatal auditory stimulation did not influence hatchability rate, body weights at ED 21 and post-hatch day (PH) 1. The MUSIC and NOISE treatments elevated HSP70 at ED21 compared to the Control, while opposite results were observed at PH1. The AGP, CPN and CORT were not significantly (p > 0.05) affected by PAS at ED21. However, at PH1, the Control ducklings showed significantly higher OVT and AGP. The NOISE and MUSIC treatments attenuated DA activity at ED21 and PH1, respectively. PAS induces a physiological stress response in embryos but does not impact hatchability or hatchling weights. Exposure to MUSIC and NOISE effectively reduces stress during incubation and hatching, enhancing stress resilience in day-old ducklings.