A. Genchev

Abstract. According to its weight traits, the population of Manchurian Golden quails bred at the Department of Poultry Science at Trakia University can be referred to the heavy all-purpose type of Japanese quails with an average live weight of 259.7–273.1 g of females and 214.3–230.3 g of males. Under optimal temperature conditions, the females of the examined population ate, on average, 42–45.2 g of feed per day, which comprised 16.9–17.3% of their live weight during the most active period of laying. The average intensity of egg-laying during the control period was 80.95%, with 78.96% of all laid eggs being fit for incubation. In absolute terms, this accounted for 168.55 breeding eggs per layer hen. The percentage of culled eggs, excluding the first production month, varied between 0.98–2.2% with a noticeable tendency towards a slight increase after the third production month. The mean egg mass varied between 12.37–13.45 g, with the average egg mass per layer hen for the 7-month control period being 1986.69 g, equal to 7.65 times the average weight of layers. The feed conversion ratio per kg egg mass for the different generations ranged within 3.45–5.05 kg per kg of egg mass, with the highest values observed during the phase of the flock’s peak egg production – 3.626±0.111. The hatchability of the incubation eggs was high, relatively stable, at levels of 78–80.87%. The percentage of vital quail hatchlings comprised 95.6–98.2% of all hatched birds. Of all culled incubation eggs, the highest share was that of dead embryos during the final incubation stage (15th–18th day) with higher percentages during the beginning of egg production (16.3%).