Shell Quality Parameters of Japanese Quail (Coturnix japonica) Eggs as Estimated by Non-Destructive Testing Technology

The quality parameters of quail eggshells find extensive utility in studies of production efficiency and basic biology. Non-destructive evaluation methods are of particular relevance. Herein, we developed a non-destructive technology for assaying such shell characteristics as shell strength (F), thickness (T), and weight (W_s). Studies were conducted using 176 eggs laid by 11-month-old quails from a resource population of F₂ crossbreds. The main set of measured and calculated parameters included egg weight (W), volume (V), and surface area (S). In addition, we determined an indicator of elastic shell deformation under a non-destructive load of 0.5 kg (δ_0.5). Use of this parameter set allowed us to make the most accurate non-invasive prediction of the values of F (R = 0.756), T (R = 0.266), and W_s (R = 0.450) for quail eggs. As a result of comparative analysis of the current and previously obtained equations for calculating W_s, the disadvantages of using empirical equations were also identified. Herewith, we proposed the so-called index approach to forming mathematical dependences, simplifying their further use, for example, in breeding studies. As such, we selected the following conditionally called indices: metabolism index (S/V) and specific elastic shell deformation (δ_0.5/W). Following the approximation, more convenient and compact dependences were produced. The correlation coefficients between the true and computed values were 0.749 for predicting F, 0.262 for T, and 0.443 for W_s, with corresponding RMSE values equal to 0.416 for F, 0.019 for T, and 0.105 for W_s. The established index representation of empirical equations will serve as a crucial instrument for eggshell quality control and application in quail breeding.