The role of maternal investment on avian offspring has considerable life history implications on production traits and therefore potential for the poultry industry. A first generation (G1) of Japanese quail (Coturnix coturnix japonica) were bred from a 2 x 2 factorial design. Parents were fed either a control or methyl-enhanced (HiBET) diet, and their eggs were treated with a vehicle or corticosterone injection during day 5 of incubation. A subset of G1 birds were subjected to an open field trial (OFT) and capture restraint stress protocol. Significant effects of HiBET diet were found on parental egg and liver weights, G1 hatch, liver and female reproductive tract weights, egg productivity, latency to leave the OFT central zone, male baseline 11-dehydrocorticosterone, and female androstenedione plasma concentrations. In ovo treatment significantly affected latency to return to the OFT, male baseline testosterone and androstenedione, and change in androstenedione plasma concentration. Diet by treatment interactions were significant for G1 liver weight and male baseline plasma concentrations of corticosterone. These novel findings suggest significant positive effects on reproduction, growth, precociousness, and Hypothalamic-Pituitary-Adrenal axis function from enhanced methyl diets, and are important in understanding how in ovo stressors (representing maternal stress), affect the first offspring generation.