EN
The aim of this study was to analyze changes in body weight and the level of serum creatinine of farm fallow deer depending on age and season of the year, and to attempt to use these results to evaluate their individual health. Research material constituted blood samples from 47 females of Dama dama fallow deer from farming stock. Blood samples were collected twice from the external jugular vein from the same individuals at two intervals - in winter and in spring. The animals were weighed at the same time, with an accuracy of 0.5 kg. Serum creatinine was determined using a spectrophotometric apparatus for the analysis of “BS 300” biochemical blood serum. After comparing the results of body-weight measurements taken in both periods, it was observed that the average body weight of fallow deer weighed in April decreased by about 4% of the value obtained at the beginning of winter. A statistically highly significant decrease in the average level of creatinine in blood serum sampled in the spring was found, which amounted to over 26% compared with the serum of blood taken in December. With the age of the fallow deer the average level of serum creatinine increased, but a significant difference was found only between one-year and seven-year old individuals. In winter the condition of individual animals deteriorates, which is illustrated by body weight loss. At the same time the level of creatinine in blood serum decreases significantly, which is a consequence of the decrease in muscle mass and reduced physical activity of animals in winter. These results indicate that the decrease in creatinine levels in blood serum in healthy animals (not associated with impaired renal function) can be used to assess the welfare of wildlife animals as an indicator of individual health deterioration.