What’s in a quail shell? That which we call an egg by any other means can be described

In egg research Haugh units (HU) are used for both chickens and other birds, despite the fact that they were derived exclusively for the former. Inspired by Shakespeare’s line “What's in a name?,” we considered the development of calculation methods specific to the Japanese quail (Coturnix japonica) egg quality. Hereby, we sought to develop destructive and non-destructive approaches to evaluating qualitative characteristics of quail egg contents, including density of the interior (D_i) and yolk weight (W_y). We used eggs laid by 11-month-old quails of an F₂ model resource population. An experimental procedure was proposed for approximating volumes of thick albumen and yolk depending on the whole egg weight, calculating formulae for a complex indicator of the quail egg contents quality, i.e., Egg Quality Index (EQI). Its computation was based on egg weight, thick albumen height and yolk height or diameter. A comparative assessment of the use of indices demonstrated the advantage of EQI over HU. Based on the empirical data, mathematical models were obtained for calculating D_i and W_y expressed as sets of indices for egg density (weight divided by volume), metabolism (surface area divided by volume), and air cell (its volume divided by egg volume). When calculating D_i, it is advisable to use indices for egg density (weight divided by volume), metabolism (surface area divided by volume) and air cell (air cell volume divided by egg volume). Of the indices assessed, W_y depended to a greater extent on the egg surface area-to-volume ratio (S/V).