Marta H Machura, Piotr A Antos
Haematological tests are essential for assessing the physiological state of the body and identifying metabolic disorders in birds. Due to the unique structure and physiological characteristics of avian erythrocytes, along with their sensitivity to endocrine influences, the interpretation of blood parameters requires consideration of hormonal regulation, particularly estrogen-dependent effects. These hormones play a significant role in erythropoiesis and modulation of the immune response. The aim of this study was to evaluate the effect of tamoxifen treatment, a selective estrogen receptor modulator, on the haematological profile and selected iron status parameters. The analysis included determination of erythrocyte parameters (PCV, RBC, Hb, MCV, MCH, MCHC), leukocyte profile (WBC, H/L ratio), as well as plasma iron concentration, TIBC, and transferrin saturation. In hens treated with tamoxifen (n = 8) for 7 continuous days at a dose of 6 mg/0.3 mL ethanol per kg of body weight, a significant increase in PCV and RBC count was observed, with no changes in Hb or MCV, compared to control hens (treated with vehicle; n = 8). Simultaneously, a decrease in MCH and MCHC was observed. These alterations were accompanied by a decrease in plasma iron concentration and transferrin saturation, with no significant changes in TIBC. Regarding the leukocyte profile, no significant changes in WBC count was observed, however, a decrease in H/L ratio was noted. The results obtained indicate that modulation of estrogen signaling may lead to changes in the hematopoietic system of laying hens and affect the availability of iron for erythropoiesis. The findings suggest a correlation between hormonal regulation, erythropoiesis, and iron metabolism in hens. The results of this study underscore the importance of considering endocrine factors in the interpretation of haematological parameters of laying hens.