Acoustic characteristics of vocalisations emitted by the domestic rabbit (Oryctolagus cuniculus) during copula ejaculation and electro-ejaculation with or without anaesthesia

Abstract

Vocalisations can be used as reliable indicators of pain, but little information is available in rabbits, where acoustic tools for farming environments can be used for welfare judgements. The aim of this study was to compare vocalisations produced during copula ejaculation and electro-ejaculation (EE), with or without general anaesthesia, in domestic rabbits. Vocalisations of nine New Zealand white adult males were digitally recorded. The number of males vocalising and vocal characteristics including high, low, maximum and fundamental frequencies and duration of the vocalisations were analysed. There were no differences in the number of males vocalising or any vocalisation parameter between the 1<sup>st</sup> and 2<sup>nd</sup> ejaculation while copulating, even though the fundamental frequency increased in all males in the 2<sup>nd</sup> ejaculation (<em>P</em>=0.008). More males vocalised while mating than while being electro-ejaculated (<em>P</em>=0.03), and all vocalisation parameters were greater during EE than while mating (<em>P</em>=0.004). The use or not of anaesthesia during EE did not modify any of the parameters evaluated. It was concluded that: 1) more males vocalised during copula ejaculation than while being electro-ejaculated; 2) bio-acoustic analysis allowed us to identify aversive utterance vocalisations, which are characterised with higher frequencies, that those from non-aversive stimulus; and 3) at least with the anaesthetic combination and the responses studied, anaesthesia had no effect on the acoustic characteristics of the vocalisation emitted during EE in rabbits.