Clinical-biochemical status of hens due to changes of battery cages height location

In the conditions of industrial poultry farming, the body of hens is constantly exposed to numerous technological stressors, the least studied of which are long-term ones, that can provoke chronic stress. One such technological stressor is an increase in the level of cage equipment, which is used by producers to obtain a larger amount of products from 1 m2 of poultry area. The aim of this work was to study the physiological state of the hen’s body based on the clinical biochemical analysis of their blood serum, depending on the battery cages height. In the conditions of a modern complex for the production of edible eggs in a poultry house with an area of 2 915 m2, 4 groups of hens were formed, each of them was kept on a separate floor-analogue in terms of area and cage equipment. Each floor was equipped with «Big Dutchman» 3-tier battery cages. Battery cages of each floor were separated from each other by a lattice floor so that cages of 1–3 tiers entered up to the 1st floor, 4–6 tiers – up to the 2nd, 7–9 tiers – up to the 3rd, and 10–12 tiers – up to 4th floor of cage equipment. Biochemical parameters and activity of hens blood serum enzymes were determined on a BioChem FC-360 biochemical analyzer. For this, 30 blood samples with a volume of 1.0–1.5 ml were taken from axillary veins of laying hens in each group at the age of 18 weeks (at the beginning of the study) and at 52 weeks. It was found that increasing the layering of cage equipment does not have a negative impact on the hen’s body. So, for keeping hens in cages of multi-tier battery cages located on floors 2–4 (4–12 tiers), the biochemical status and activity of their blood serum enzymes were within the physiological norm. Whereas, for hens kept in battery cages of the a multi-tiered system on the 1st floor there was an increase in glucose levels of 60.5–71.0%, creatinine – by 9.7–12.3%, phosphorus – 82.6–100.0%, was observed a decrease in calcium to phosphorus ratio 46.7–50.0%, which was confirmed by an increase in the activity of alkaline phosphatase by 22.3–27.0%, as well as an increase in the activity of aspartate aminotransferase by 3.2–13.8%, lactate dehydrogenase - by 48.5–65.1% and gamma-glutamyl transferase – by 16.4–20.6%. It has been proven that the main consequences of chronic stress caused by keeping hens in the lower floor cells of the multi-tiered battery cage are reflected in the biochemical parameters of their serum, namely increased glucose, creatinine, enzyme activity and violation of calcium to phosphorus ratio.