Abstract
The influence of hen layer density on the variability of the number of red blood cells, heterophiles and lymphocytes in the blood, the secretory activity of adrenal glands, estimated by the level of corti-costerone and cortisol, as well as the presence of interrelations between hormones and blood cells by calculating complex indices, were studied. Chickens, as the research object, were kept in cages, under conditions of standard layer density and increased by 1.5 and 2.0 times. We found that chickens adapt to an increase in layer density by one and a half times, pro-vided that egg production decreases to 33.33%; two times exceed of the regulatory requirements for laying does not correspond to the adaptive abilities of birds. Depending on the level of layer density excess (stress factor) in chicken blood, the concentration of corticosterone and cortisol increases, determining a decrease in the number of lymphocytes and an in-crease in heterophiles against the background of the preservation of red blood cells, reflecting the “energy price” of adaptation. Corticosterone af-fects the relationship of red blood cells with lymphocytes and heterophiles, determining the variability of the values of the indices reflecting the ratio of red blood cells and lymphocytes (ISEL), red blood cells and hetero-philes (ISEG), red blood cells, lymphocytes and corticosterone (ISELC), red blood cells, heterophiles and corticosterone (ISEGC) and the integral index of red blood cells-heterophiles-lymphocytes and corticosterone (IIEGLC).
Highlights
In the conditions of industrial poultry farming, the body of bird is often exposed to technological stress factors, among which a special place is occupied by heat stressors [1]
We found that in the conditions of exceeding the standard density of birds laying in the cage by 1.50 times, only during the first 4 hours of the stress reaction, the chickens showed activity to restore their social status, and a certain zone of "conditional comfort" was reached between the individuals in the cage, allowing them to maintain thermal regulation of the body, take food and water
Chickens adapt to an increase in planting density by one and a half times, but the "price of adaptation" is a reduction in egg production to 33.33%
Summary
In the conditions of industrial poultry farming, the body of bird is often exposed to technological stress factors, among which a special place is occupied by heat stressors [1]. The effects of heat stress are described in the scientific literature [2, 3], the main mechanisms of its development are still not fully understood. This is due to the fact that it is initiated not by one, but, most often, by several factors or their complex. This affects the productive qualities of poultry, including growth processes, reproductive abilities and egg production, and product quality.
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