KRASTINA KALIASHEVA; MAGDALENA OBLAKOVA; PAVLINA HRISTAKIEVA; NADJA MINCHEVA; MITKO LALEV
Agricultural Academy, Agricultural Institute, Hybrid Centre of Poultry Breeding, BG- 6000 Stara Zagora, Bulgaria
Kaliasheva, K., M. Oblakova, P. Hristakieva, N. Mincheva and M. Lalev, 2017. Comparative study on morphological qualities of eggs from new autosexing layer hybrids for free range poultry farming system. Bulg. J. Agric. Sci., 23 (4): 609–616
The aim of this study was to evaluate fi ve genotypes autosexing layer hybrids by feathering colour, obtained from the rich gene pool of layer hens, adapted to raising in free range poultry farming system. One of the related tasks was to establish the infl uence of the genotype on morphological quality of eggs in the fi ve hybrid groups as an element of evaluating their egg production performance. Experiments were performed at the Agricultural Institute – Stara Zagora in 2015. Eggs were collected from fi ve genotypes autosexing hybrid hen strains (by feathering colour). Hybrids crosses were obtained from the following lines of the national gene pool- line Ss (Sussex- Columbian feathering), line NHG (German New Hampshire – red feathering), line P (Rhode Island Red, red feathering), line Е (Barred Plymouth Rock), line I (Barnevelder). For the purpose of investigation morphological traits of eggs, 30 eggs were obtained from 34-week- old layers from each of the fi ve groups. The eggs produced by hybrids from group V were the heaviest – 62.47 g with Barred Plymouth Rock as maternal form, whereas eggs of group IV (line Ss: Sussex as maternal form) were the lightest – 53.50 g at p<0.001. The eggs of the other hybrid groups were at the intermediate level. The weight of the shell with shell membranes had a highest signifi cant value in heaviest eggs- those of hybrids groups I, V, II (6.14 g, 6.13 g and 6.01 g respectively). The egg weight correlated to the shell percentage. The differences were signifi cant at various levels of signifi cance (р < 0.05). The absolute yolk weight did not tend to increase in eggs with higher weight. The trait varied at a various extent among the hybrids groups. The yolk index was not associated to egg weight and yolk weight. The groups with highest egg weight to yolk weight ratio were not the heaviest ones. The eggs of studied hybrids with the highest egg weight had more albumen. In group II, its amount was 36.54 g, group V – 35.83 g, group I – 35.12 g with highly statistically signifi cant differences between groups III and IV.