Site- and age-related changes in blood count parameters in Apodemus flavicollis during short-term monitoring

Abstract

Blood count values vary between individuals of the same species due to individual predispositions, as well as in response to exogenous factors. In addition to individual components of blood count, red blood cells respond to these environmental changes by their size and shape. However, these changes are less visible and occur more slowly. In this study, we focused on comparing the blood counts of yellow-necked mice (Apodemus flavicollis) during a month-long study (August 2018) in the vicinity of the city of Žilina. The first group of individuals came from the polluted site of a heating plant tailings impoundment, this is a waste fly ash storage site. The control site was selected based on habitat similarity approximately 1 km from the tailings pond. Morphological parameters of individuals, blood count parameters and erythrocyte size (cell length, cell width) were analyzed using principal component analysis (PCA). The resulting factor score was compared with location, age and sex. While no significant differences were found by gender, locality and age were significant variables that correlated with the factors. Animals at the tailings site showed higher HGB, MCHC and PLT values (Factor 1) and similarly, animals at the tailings site were smaller, had fewer granulocytes and had higher lymphocyte values (Factor 2). Age was significantly related to Factors 2 and 4. Two-year-old animals were larger, had fewer granulocytes, and more lymphocytes (Factor 2). Two-year-olds with longer paws and longer ears have higher MCH and MCV, but fewer WBCs (Factor 4). Although RBC size and width were related to two factors found (Factors 3 and 6), these factors did not related with location, age or sex.