The present study was carried out to monitor the reproductive traits of Japanese quail breeds reared in Bulgaria. The quail breeds kept at the Poultry Breeding Section at Trakia University: Pharaoh and Manchurian Golden, were used. Breeder flocks consisted of 8 female and 3 male birds. The eggs from each
breed were collected for three consecutive days in the middle of every production month. The incubation was performed under standard conditions in a smallscale
industrial incubator (Victoria-560). For the entire experimental period, 3902 Pharaoh and 3617 Manchurian Golden quail eggs were incubated. The
average percentage of hatched vital quails during the 7-month experimental period was 75.70% in the Pharaoh and 75.97% in the Manchurian Golden breed.
The incubation waste in both breeds consisted mainly of infertile eggs and late embryonic deaths – 18.66% and 18.52% of incubated Pharaoh and Manchurian
Golden eggs, respectively. During the first production month, the hatchability of incubated eggs was statistically significantly lower (P<0.001 in Pharaoh and
P<0.01 in Manchurian Golden quails) mostly due to the late embryonic deaths.