The use of vocalisation sounds to assess responses of broiler chicken to environmental variables

The vocalisation sounds of broiler chicken have been studied previously; however, in this study we describe the monitoring of broiler chicken vocalisation under normal farm conditions, with sound recorded and assessed at regular intervals throughout the life of the bird from day 1 to day 37 to assess whether recognisable, and even predictable, vocalisation patterns, based on frequency and bandwidth analysis, are evident in birds at different ages and stages of growth within commercial broiler production timescales. Two experimental trials were carried out in a ‘conventional’ indoor reared broiler farm, and the audio recording procedures lasted for 38 days. The recordings were made at regular intervals with the equipment in the same position inside the broiler house during each period of data collection. The recordings were made automatically, without the presence of human operators, using a professional hand-held solid state recorder (Marantz PMD 661 MK II) and provided sound recordings which represented situations without disturbance of the birds beyond that created by the farmer. Digital files of one hour duration were cut into short files of 10 minutes duration, and these sound recordings were analysed and labelled using analysis software: Adobe Audition CS6. Analysis of the sounds recorded, using audio software, identified that the sounds and the related frequencies changed in relation to increasing age and the weight of the broilers. Statistical analysis (Proc CORR, SAS) showed a significant correlation (P<0.001) between the frequency of vocalisation and the age and behaviour of the birds. This method, based on identification of specific frequencies of the sounds emitted compared with age and weight could potentially be used in a system to evaluate the health and welfare status of birds at farm level.