Realization of hens’ potential productivity under the influence of group size

Abstract

The parameters of the group size of laying hens of the industrial herd in cages are not provided by current domestic standards, and according to the recommendations of the cross developer should be at least 7 birds, although in practice they reach 100 birds, so they need to be clarified when using 12-tier cage batteries. The aim of the research was to study the influence of the group size of hens on their productivity with the same density of laying hens in similar cages by design. To do this, in a modern complex for the production of eggs we formed 4 groups of hens, each of which was kept in a separate poultry house-analogue in area and equipment, equipped with 12-tier cage batteries, the size of the cages in which differed. The hens’ group in each cage of the 1st group contained 93 birds, the 2nd group — 52 birds, the 3rd — 17 birds and 4th — 9 birds. It was found that the maximum realization of laying hens productivity of modern white-egg crosses during their keeping in cages of 12-tier cage batteries was observed for the 52–93 hens’ groups which allows for a 44-week period of use to receive an additional 13.3–48.2 million eggs from each poultry house (4.5–16.5 thousand eggs per 1 m2 of its area) compared to the group size 9 hens, at the highest level of the European coefficient of efficiency of their production by 1.6–2.8 units. It is shown that the group size 17 hens is insufficient for the formation of a strategy of social tolerance in hens and is accompanied by stressful conditions, which are manifested in a decrease in the preservation by 1.7–2.1%, body weight — by 2.6–3.4 %, laying on the initial laying hen — by 3.9–8.4% and on the average laying hen — by 4.3–4.4%, as well as a reduction in feed costs by 1.5–1.6%, which leads to a decrease in gross output eggs by 4.4–39.3 million eggs and egg mass — by 291.9–2508.6 tons from each poultry house, including 1.5–13.5 thousand eggs and 100.1–860.6 kg per 1 m2 of its area, reducing the yield of egg mass per initial laying hen by 0.7–1.5 kg with a decrease in the level of the European coefficient of efficiency of egg production by 1.0–2.2 units. While the keeping of laying hens in groups of 9 hens causes the development of chronic stress through the formation of a system of stable hierarchy and possible despotic behavior, the consequences of which are a decrease in preservation by 4.4–6.5%, body weight — by 2.1-5.4%, egg production at the primary — by 2, 8–11.0% and for the average laying — by 3.8–8.0%, as well as a decrease in feed costs by 2.0–3.6%, which causes a decrease in the gross yield of eggs by 8.9–48, 2 million eggs and egg mass — by 552.0–3060.5 tons from each poultry house, including 3.0–16.5 thousand eggs and 189.4–1050.0 kg from 1 m2 of its area, reduction of egg yield per initial laying hen by 0.4–1.9 kg with a decrease in the level of the European coefficient of egg production efficiency by 0.6–2.8 units.