Vocalisations and acoustic parameters of flock noise from feather pecking and non-feather pecking laying flocks

Abstract

1. In this study, the calling rates of vocalisations known to indicate distress and aversive events (Alarm calls, Squawks, Total vocalisations) and acoustic parameters of flock noise were quantified from feather and non-feather pecking laying flocks.

2. One hour of flock noise (background machinery and hen vocalisations) was recorded from 21 commercial free-range laying hen flocks aged ≥35 weeks. Ten of the flocks were classified as feather pecking (based on a plumage condition score) and 11 as non-feather pecking.

3. Recordings were made using a Sony DAT recorder and Audio-Technica omni-directional microphone, placed in the centre of the house—1·5 m from the ground. Avisoft-SASlab Pro was used to create and analyse audio spectrograms.

4. There was no effect of flock size or farm on call/s or acoustic parameters of flock noise. However, strain had an effect on the number of Total vocalisation/s; the Hebden Black flock made more calls than Lohmann flocks. Feather pecking flocks gave more Squawk/s and more Total vocalisation/s than non-feather pecking flocks. Feather pecking did not explain variation in alarm call rate or, intensity (dB) and frequency (Hz) measures of flock noise.

5. The differences between Squawk and Total vocalisation call rates of feather and non-feather pecking flocks are a new finding. An increase or change in flock calling rate may be evident before other conventional measures of laying hen welfare such as a drop in egg production or increase in plumage damage, thus enabling farmers to make management or husbandry changes to prevent an outbreak of feather pecking.

Acknowledgements

Thanks to J.R. Waas at University of Waikato, Hamilton, New Zealand for advice on audio recording and vocalisation analysis. M.S. Dawkins, T.A. Jones, K. Drake and an anonymous reviewer commented on and significantly improved earlier drafts of this manuscript. Dean's Foods Ltd provided a travel and accommodation grant. The Worshipful Company of Poulters’ Charitable Trust provided an equipment grant. A. Bright was supported by a Top Achiever Doctoral scholarship from the New Zealand government's Tertiary Education Commission.