External egg quality from Siciliana, a native chicken breed of the Sicilian Region (Italy) reared under free range conditions

Animal biodiversity is an important component of all sustainable agri-food systems. The valorisation of typical products also represents a strategy for the preservation of local breeds. Aim of this study, taking into account the visual criteria of consumer choice, was to evaluate the external characteristics of eggs from the endangered Siciliana (SI) chicken breed compared to Livorno (LI) pure breed and Lohmann white (LW) commercial hybrid ones. No. 63 eggs (21 for each group) were sampled from 3 flocks of 2 local Italian breeds (SI and LI) and 1 commercial strain of LW, all reared in different farm under organic conditions. The following external quality traits were evaluated: egg’s weight, length, width, circumference, shape index, shell percentage, and shell index. Eggshell color was determined using a colorimeter (Minolta CM 500) and results were expressed using the CIE L*a*b* system color profile. Furthermore, the image of each eggshell was acquired with a computer vision system (E-eye, Iris visual analyzer 400, Alpha MOS) and results were expressed using the RGB system color profile. E-Eye data were subjected to PCA analysis. As expected, the average weight of the 2 autochthonous breeds eggs was similar (SI =56.80g; LI =61.23 g) and significantly (p <0.0001) lower than LW eggs (70.33 g). Moreover, the width and circumference of SI group eggs (41.33 and 1440mm, respectively) were significantly lower than LI (43.39mm; 15.04mm) and LW (45.27mm; 15.55mm) groups; therefore, the shape index of SI group eggs (69.21%) was significantly (p <0.0001) different from LW and LI (74.17% and 75.92%, respectively) groups. No significant differences were found for shell percentage and shell index. Regarding shell color, all parameters of SI group (L=91.88; a=-0.26; b=10.29) significantly differed (p <0.0001) from LI (L=94.36, a=-0.87, b =6.83;) and LW (L=94.45, a=-0.61, b=6.07) groups. Results from E-eye showed 5 color codes (2184, 2439, 2455, 2456, 2712) founded only in eggshell of SI and the PCA plot has clearly separated the groups, showing SI at right side of the first component and LW and LI on the left one. Overall, the results, showing how the shape and color of the shell may characterise a breed directing consumers in their choices, can be also taken into account for the conservation and characterisation of a native Sicilian breed