Assessment of Residual Feed Intake and Its Relevant Measurements in Two Varieties of Japanese Quails (Coturnixcoturnix japonica) under High Environmental Temperature

SIMPLE SUMMARY: Residual feed intake (RFI) is an important factor in improving poultry production and laying performance, particularly for poultry raised under heat stress. An experiment was conducted to assess RFI and its related measurements in Japanese quails (Coturnixcoturnix japonica) of two varieties (gray and white) reared under high environmental temperatures.The current results confirmed that raising gray quails for egg production under high environmental temperature is recommended. Multiple regression analysis clearly identified a significant effect of metabolic body weight and egg mass for the computation of expected feed intake rather than body weight gain in both varieties of Japanese quails. ABSTRACT: Three hundred and ten 12-week-old laying Japanese quails (Coturnixcoturnix japonica) from gray and white varieties (155 each) were randomly selected from the initial population and kept in individual battery cages. The measurements of growth and egg production were determined to derive residual feed intake (RFI). The relationship between RFI and egg quality, blood parameters, and carcass characteristics was also determined. The results indicated that the gray quails had significantly higher egg mass and lower broken eggs compared to the white quails. A significant increase of eggshell strength and shell percentage was found in eggs produced from gray quails compared to their white counterparts, although their shell thickness means weresimilar. The results of multiple regression analysis clearly identified a significant effect of metabolic body weight and egg mass for the computation of expected feed intake, rather than body weight gain, in both varieties of Japanese quails. A strong positive correlation between RFI and feed intake in both gray and white quail varieties was found. The same trend was also observed for feed conversion ratio (FCR). Therefore, including RFI in the selection criteria of Japanese quails in order to improve FCR under high environmental temperature is highly recommended.