Age and breed variation in post‑weaning lamb vocalisations and vocal individuality

Vocal communication is important for social interactions in sheep, yet knowledge about lamb vocal behaviour during early development remains limited. This study aimed to examine vocalisation changes, breed differences and vocal individuality in bleats of lambs during the post-weaning period. High-pitched vocalisations of lambs (n = 18) from three dairy sheep breeds were recorded at three developmental time points (112, 154 and 196 days old). Twenty‑four acoustic parameters were extracted and entered into a principal component analysis, followed by linear mixed models to evaluate the effects of breed, age and body size on acoustic characteristics. Discriminant function analysis were further applied to examine vocal individuality. Breed influenced components related to energy distribution and formant frequencies, while age affected maximum formant frequencies, fundamental frequency and call duration. The examined breeds showed similar developmental patterns in the acoustic parameters. Discriminant analysis revealed modest individual classification. Individuality was also maintained across the examined time points. Vocal characteristics also showed meaningful variation between breeds, indicating that breed-specific acoustic patterns can be distinguished alongside individual signatures. The results demonstrate that lamb vocalisations are shaped by both developmental and breed-related factors while maintaining lasting individual acoustic signatures.