Acoustic Features of Pain-Induced Vocalisations Are Associated with Subsequent Growth and Temperament Following Thermal Disbudding in Goat Kids: A Preliminary Study.

Whether vocalisations during disbudding predict later outcomes in goat kids is unknown. In this preliminary study, we allocated 18 female Tianfu goat kids to disbudding (n = 9) or sham (n = 9). Disbudding used a hot iron without analgesia; sham kids received an unheated iron. Vocalisations, tail flicks, and struggles were recorded. Fundamental frequency (F0) and Mel-frequency cepstral coefficients (MFCCs) were extracted. Body weight and temperament were assessed at 90 days post-procedure; home-pen behaviour was scan-sampled at 60 and 90 days post-procedure. Two kids were excluded due to insufficient recordings, leaving 16 (9 disbudded, 7 sham). Disbudded kids vocalised more frequently (14.5 vs. 8.1 calls/min, p = 0.0007) and had lower minimum F0 (283.4 vs. 366.1 Hz, p = 0.020), with significant MFCC shifts. Several acoustic features correlated with body weight at 90 days post-procedure (mfcc_12_std: r = 0.903, p = 0.001) and temperament (mfcc_2_mean: r = -0.788, p = 0.012) after controlling for disbudding weight. The first principal component of acoustic features (PC1) correlated with lower body weight at 90 days post-procedure in disbudded kids (r = -0.786, p = 0.036), but not in shams (r = -0.257, p = 0.623). No subgroup differences were found in home-pen behaviours. These findings indicate that acute pain vocalisations may reflect individual stress reactivity-a possible 'vocal phenotype'-and, with validation, could inform non-invasive screening for at-risk kids.