It is essential to understand and manage environmental factors for good quail production and welfare. One of the most important environmental stressors that hinder quail productivity is heat stress. This study aimed to evaluate the impact of spraying Japanese quail (Coturnix coturnix japonica) eggs with betaine after exposure to short-term high temperature during early embryogenesis on pre and post-hatch performance of quail. A total of 750 eggs were equally divided into two groups. Eggs in the first group were incubated at normal incubation temperature (37.5 °C/NIT), while those in the second group were incubated at high incubation temperature (39.0 °C/HIT) for 3 h daily from day 4–6 of incubation. Eggs in both groups were subjected to five treatments, NC (negative control), PC sprayed distilled water (positive control), while B0.5, B1, and B2 treatments were sprayed with distilled water supplemented with 500 …