Regularity of formation of egg productivity of hens depending on their live weight at the beginning of photostimulation

Abstract

Goal. To assess the regularity of the formation of egg productivity of hens of the Ukrainian gene pool population Birkivska barvysta depending on their live weight at the beginning of photostimulation. Methods. The experiment was carried out on hens of the Birkivska barvysta population of the egg production line for 34 weeks. At the age of 17 weeks, young birds were divided into 3 experimental groups depending on their live weight: light (1.11–1.35 kg), medium (1.36–1.51 kg), and heavy (1.52–1.90 kg) weight groups. The control was a mixed group of birds, not divided by live weight (1.06–1.90 kg). In the future, the birds were kept within the classification groups, and the indicators of egg productivity and the parameters of its formation were evaluated. Results. The distribution of young birds into balanced groups contributed to a significant decrease in the variability of live weight in the experimental groups by 1.9–3.2 times. Further keeping of the hens within the defined groups had a positive effect on their egg productivity, which was generally 4% higher in the experiment compared to the control. In the experimental birds, the laying rate from the beginning of egg laying to its peak increased faster (by 0.8% per week), and decreased more slowly compared to the control (by 0.03% per week). The experimental hens were more intensively laying eggs. Their superiority over the control was also established for the average daily and relative gains, the growth stress index, and the intensity of laying eggs. Negative correlations of the live weight of young birds at the beginning of photostimulation with egg-laying (– 0.29), intensity of its formation (– 0.19), average daily (– 0.29) and relative (– 0.70) growth, uniformity index (– 0.17), stress (– 0.25) and stability (– 0.46), as well as a high positive correlation with the rate of decline in egg-laying intensity (0.46), indicate a close inversely proportional relationship between the live weight of birds at the age of 17 weeks and its subsequent egg productivity. This is confirmed by the highest laying capacity in the light group D1 and its decrease in other groups by 9.1–12.5% with an increase in their live weight by 12.5–27.3%. Conclusions. An obvious advantage of keeping chickens in balanced groups is the improvement of egg-laying in experimental birds (up to 4%). The intensity of the formation of egg productivity and the level of realization of the genetic potential largely depends on the live weight of young birds at the beginning of photostimulation. This is confirmed by the close inversely proportional relationship between this indicator and the egg-laying capacity, its average daily and relative increase, indices of stability, uniformity, and growth tension. The fact that lighter birds have higher laying rates and vice versa should be taken into account when determining the optimal live weight of chickens for the formation of an adult flock.