Multidimensional characterisation of phenotypic traits in three slow-growing native chicken breeds

To support the recent consumers’ growing demand for local, alternative, and sustainable products, this study focused on the comprehensive characterisation of three slow-growing chickens from Piedmont (northwest Italy): Bionda Piemontese (BP), Bianca di Saluzzo (BS), and Millefiori Piemontese (MP). At 29 days, birds were divided into pens by sex and breed (10 birds/pen; 6 replicates/sex for BP and BS; and 4 replicates/sex for MP). Up to 181 d, live weight (LW) and feed consumption were assessed biweekly to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR). Behavioural traits were assessed monthly through avoidance distance (AD), novel object (NO), and tonic immobility (TI) tests. Growth curves were evaluated using the Gompertz model, and morphometric traits were studied from 71 days to 225 days. LW differences were observed among breeds and sexes, especially during the early growth phases; BP males were the heaviest, followed by BS and MP. Sexual dimorphism became evident at 57 d, as males presented greater morphometric traits and ADG (p < 0.001). Over time, ADFI varied by breed and sex (p = 0.013). FCR was higher in females than males (p = 0.001). At 71 d, PCA of morphometric traits showed increasing separation by sex and breed thereafter. In general, behavioural analyses indicated differentiation by sex, breed, and time. No differences were observed for AD; however, BS showed lower NO responses (p = 0.047), and BP exhibited the shortest TI durations (p < 0.001). Although data on MP remain limited, the three Piedmontese breeds demonstrated competitive growth and distinct behavioural profiles.