External Characteristics of Eggs From Three Subspecies of the Common Pheasant (Phasianus Colchicuslinnaeus, 1758) Reared in Captivity in Bulgaria

Basic external morphometric characteristics, including a detailed colorimetric analysis, were studied in eggs from three subspecies of the Common Pheasant (Phasianus colchicus Linnaeus, 1758), reared for restocking purposes in Bulgaria. A total of 120 fresh eggs from each of three Common Pheasant subspecies bred in captivity on pheasant farms in Bulgaria were collected to evaluate external egg characteristics. Morphometric traits, such as weight, major and minor axes were measured to calculate the egg shape index and shell surface area. Eggshell colour was assessed using the CIE L*a*b*colour space, and additional parameters, such as chroma and shell colour index were also calculated. Significant differences were observed among the subspecies in terms of egg weight, minor axis length, and shell surface area (p< 0.001). The colorimetric analysis revealed statistically significant differences in all examined shell colour traits between Phasianus colchicus karpowi Buturlin (1904) and the other two subspecies - Phasianus colchicus mongolicus Brandt (1844) and Phasianus colchicus colchicus Linnaeus (1758) (p< 0.05). The study revealed significant inter-subspecific variation in egg morphometric and shell colour traits, with P. c. karpowi differing markedly from P. c. mongolicus and P. c. colchicus.