Sound exposure and its beneficial effects on embryonic growth and hatching of broiler chicks.

1. The physical factors that involve artificial incubation determine embryonic growth and hatching of broiler chicks, and have important implications for the poultry production chain and chick welfare. This study explored the effects of sound exposure on incubation responses (hatching, embryonic development and chick quality).2. A 2 × 2 factorial experiment with the factors 'sound pressure level' (at 70 and 90 dB) and 'species-specific vocalisations' (at 75dB - 85dB) was performed in four experimental incubators (loaded with 90 eggs each) for eight consecutive cycles of incubation, totalling 2880 Cobb-500® broiler breeder eggs.3. Embryonic growth was not influenced by any experimental factor, but the highest sound pressure level (90 dB) led to earlier hatching, higher hatchability, better chick quality and lower weight at hatching. Additional effects of species-specific vocalisations were found at 70 dB noise, which caused early hatching and better chick quality.4. It was concluded that the loud noise found in commercial hatcheries (at 90 dB) can be beneficial. Furthermore, the presence of species-specific vocalisations could improve the hatching time and chick quality from experimental incubators (at 70 dB). However, this would not provide additional benefits in commercial hatcheries, due to the machinery noise masking them.