Chick Embryo Development Rate in Response to Light Stimulus

Crossbred and purebred embryos in brown- and white-shelled eggs were incubated under light and dark treatments. Embryos developed under lights were significantly (P ≤ .01) larger than those developed under dark conditions at 15 days of incubation. The rates of weight increase over days accelerated differentially in the two treatments, but treatment effects were not altered by shell color or breed of parents. Hatching time of illuminated embryos was significantly (P ≤ .01) reduced by an average of 5 hours.