Exploring skull shape variation and allometry across different chicken breeds

This study investigates skull shape variation and allometry among three different chicken breeds: Broiler, Lohman Brown, and Leghorn. Geometric morphometrics analysis was employed to analyse skull morphology, focusing on facial bones and the neurocranium. The study aims to understand how skull shape differs between these breeds and how it relates to size variation. Results show significant differences in skull morphology among the chicken breeds. Following PCA analysis, it was observed that PC1 explained 21.7% of the total variation. The PC1 values of Broiler chickens were notably lower compared to other breeds, indicating distinct morphological differences in their cranial shape. Increasing PC1 values corresponded to a more rounded head shape, with individuals possessing high PC1 values exhibiting a higher neurocranium. In contrast, Lohman Brown and Leghorn chickens show similarities in skull shape, with a more elongated appearance. Broiler chickens were found to be the smallest among the breeds studied, with statistical analysis confirming their distinguishability based on centroid size. In contrast, Lohman Brown and Leghorn chickens exhibited similar sizes, with no significant difference between them. Allometric analysis reveals that skull shape changes with size, particularly in the neurocranium and facial bones. These findings suggest that evolutionary adaptations and breeding practices have influenced the skull morphology of these chicken breeds. Overall, this study provides insights into the skull shape variation and allometry of different chicken breeds, highlighting the importance of considering both genetic and environmental factors in understanding morphological diversity in poultry.