Status quo analysis of noise levels in pig fattening units in Germany

This study was conducted within the MulTiViS-project consortium on multivariate animal welfare assessment. The aim of this investigation was to perform a status quo analysis of the noise level in fattening pig farms (n = 214) and to evaluate the suitability of noise as an animal welfare indicator. In 755 conventional fattening compartments, noise measurements were carried out for one minute at animal height using the Acoustic Analyser XL2, including microphone M2210 (NTI Audio, Schaan, Liechtenstein). In addition, various animal health and environmental factors of 33,668 pigs were recorded in randomly selected pens (n = 1,668) of these compartments. The mean equivalent noise level was 70.2 +/- 5.2 dB (min 52.5, max 92.4 dB). Noise levels in compartments housing older pigs were higher (72.0 +/- 5.2 dB) than those in compartments housing younger pigs (68.5 +/- 4.7 dB, ***P < 0.001). Compartments in which the pigs were fed liquid feed were louder (70.3 +/- 4.1 dB) than compartments with dry feed (67.5 +/- 6.9 dB, ***P < 0.001). Slightly more noise was caused by partially slatted floors (70.3 +/- 6.7 dB) compared to fully slatted floors (70.2 +/- 5.0 dB, **P < 0.01), whereas straw bedding tended to reduce the noise level. In addition, the noise level in diffuse fresh air systems was lower (66.7 +/- 5.1 dB, **P < 0.01) than in all other ventilation systems. There were no statistical associations identified between animal health factors (e.g. tail biting, ear biting, superficial skin lesions and Bursa auxiliaris) and noise levels. The present study provided useful indications on the status of the noise level in fattening compartments.