Variability of the mass of eggs of the parent herd of meat and egg-laying hens and the degree of its consolidation

Abstract

Goal. To carry out a comprehensive analysis of the mass of eggs of the factory line of meat and egg-laying chickens of the Plimutrok white breed of Ukrainian breeding and to study the level of its consolidation. Methods. The research was conducted in 2024 in the conditions of the experimental farm of the State Poultry Research Station of the Institute of Animal Husbandry (SPRS IAH) of NAAS on meat and egg-laying hens of the factory line G2 of the domestic Plimutrock white breed. They studied the dynamics of egg mass and its intra-family variability (at the age of 26, 30, and 34 weeks) with the involvement of retrospective data from previous years. Egg mass was estimated by individual weighing. Based on the results of the assessment, the families were divided into classes, using the line average of the intrafamily variability of egg mass and the standard deviation. The level of line consolidation was determined using the phenotypic consolidation coefficient. Results. An increase in the average weight of eggs with increasing age of birds (from 50.7 g at 26 weeks to 60.6 g at 34 weeks), high intrafamily variability of egg weight (7.0 – 8.1%), and deterioration of these indicators in generations was observed. The coefficient of phenotypic conso­lidation of the current generation did not exceed 8.97% and was 1.5% lower than in the previous ones. The analysis of the classification of families by the level of egg weight variability showed the presence in the line of about 50% of families with indicators below 7% (classes 1 and 2) and a significant decrease in their number in the offspring (by 23%), which indicated the degradation of the level of consolidation of the factory line. However, the stability of low intrafamily variability in egg weight with age in 31.9% of families and the intergenerational correlation coefficient at the level of 0.68 indicated the potential effectiveness of selection on this parameter for line consolidation for egg weight. Conclusions. The G2 factory line of meat and egg-laying hens has a low level of consolidation in terms of egg mass and needs selection measures to increase it. The use of intrafamilial variability in egg mass during selection will contribute to the narrowing of the phenotypic variability of egg mass in the offspring and the consolidation of the herd for this selection trait.