Hematological indicators and leukocyte indices of laying hens under temperature stress

The effect of heat stress on 36-week-old Dekalb White laying hens has been studied. A stress factor lasting 48 hours caused a change in clinical signs, physiological parameters and hematological parameters. Laying hens of the experimental group were fed a feed additive based on dried live yeast Saccharomyces cerevisiae var. boulardii to reduce the negative effects of hyperthermia. In individuals of the control group, the degree of negative impact of elevated temperature was more pronounced. This was characterized by an increase in body temperature, an increase in heart rate, respiratory rate compared to the bird from the experimental group. Significant changes in hematological parameters during the stress period - an increase in the number of heterophils by 1.32 times, basophils by 1.87 times, monocytes by 1.25 times were observed in the blood of laying hens of the control group. By calculating leukocyte indices, the state of general resistance and the resources of adaptation of the body to hyperthermia were determined. The development of adaptive reactions, but with varying degrees of intensity, was confirmed by the revealed variability of these indices in birds of both groups. In laying hens from the control group, they testified to the maximum intensity and duration of the stress state. In the birds of the experimental group, there were no changes (Krebs index, leukocyte index of intoxication), or they corresponded to a mild degree (indicator of condition and lymphocytic-granulocytic index).