The impact of domestication process on eggshell microstructure in Gallus gallus, Anser anser and Anas platyrhynchos

<br />The domestication process has had asubstantial and varied impact onanimals interms ofanatomy, physiology, and behaviour. Poultry species are particularly important for humans, with the most significant being chickens, geese, and ducks. However, itisnot well understood whether, ortowhat extent selection influences the eggshell structure compared towild ancestors. Inthe present study, wecompared eggshells from three species: Red junglefowl and its four domesticated forms: Green-legged partridge, Lohmann Brown, Ko-Shamo, meat type breeder (Cobb 500); Greylag goose, and two domesticated breeds: Bilgoraj goose and White Koluda goose, aswell asMallard duck and domesticated crossbred KhO-01. The analyses revealed significant differences inthe eggshell structure both between species (<i>P</i><0.001) and between breeds (<i>P</i><0.001 for chickens and geese, and <i>P</i>=0.039 for ducks). Domesticated forms tend tohave fewer mammillary knobs per mm² (<i>P</i>=0.004), which were larger (<i>P</i><0.001) and they show the smaller coverage ofthe mammillary knobs (<i>P</i><0.001). Analyses showed significant correlations ofthe body mass and egg size with eggshell characteristics (<i>P</i><0.001). Considering that domesticated forms are usually larger, itcannot beconclusively determined whether changes instructure result from the domestication process itself orare physiologically linked tobody mass and egg size. The relatively high similarity between the eggs ofthe wild ancestor and the Ko-Shamo breed, which exhibits substantial morphological changes but has abody mass similar tothat ofthe Red junglefowl, supports this interpretation.