The study took place at the poultry Hybrid Center in the Agricultural Institute – Stara Zagora, during 2009-2010. The following lines were studied: Line K, Line L, Line G of the White Plymoth Rock breed. In each line 20 flocks were formed with 10 hens, one main and one reserve rooster. The present study was carried out to identify and compare the productivity of broiler chickens constituting a part of the poultry population at the Hybrid Center in Stara Zagora.
The live weight of young fowls from line K at 6 weeks of age was higher than that of the adolescent birds from the other two lines by 3% in females and 5.73% in males.
The number of laid eggs with the hens from line K by the 44th week of age was the highest and exceeded that of line G and line L by 4.86% and 4.47% respectively.
The fertility of the eggs and hatchability of chickens was higher in line L – 89.55% and 94.04% respectively.