Threshold values of acoustic features to assess estrous cycle phases in water buffaloes (Bubalus bubalis)

The present study was conducted to observe changes in acoustic parameters and to find out threshold values of Murrah buffaloes acoustic features during four phases of estrous cycle. Voice samples were collected from thirty healthy buffaloes, maintained at Livestock Research Centre, ICAR-National Dairy Research Institute, Karnal, Haryana, India. The acoustic features viz. call duration (sec.), intensity (dB), formants (Hz), pitch (Hz), number of periods, number of pulses, mean noise/harmonic ratio (%) were extracted with the help of PRAAT 5.1.36 software package. Mean values of call duration, intensity (mean, minimum, maximum), pitch (mean, maximum), formants (F1, F2, F3, F4, F5), mean noise to harmonic ratio were found significantly (p < 0.05) different between estrus and non-estrus phase in buffaloes. Threshold values of call duration (2.18 s.), mean intensity (72.97 dB), minimum intensity (61.42 dB), maximum intensity (81.99 dB), formants (F1- 1281.29 Hz; F2- 2433.72 Hz; F3- 3844.00 Hz; F4- 5255.32 Hz; and F5- 6648.74 Hz), mean pitch (130.67 Hz), maximum pitch (177.58 Hz), mean noise/harmonic ratio (7.47%), for estrus phase of buffaloes were determined to be cutoff points for estrus phases. The accuracy of threshold values for correctly identifying estrus voice v/s non-estrus voice was found to be 95%. Thus, present study reflected that acoustic feature's threshold values might be used as cut off points for development of algorithms for audio-sensitive softwares or Decision Support System for getting an alert about estrus phase in water buffaloes at right time in a non-invasive way.