Selected haematological indices in farmed male fallow deer (Dama dama) depending on the different conditions during the wintering period

Fallow deer (Dama dama) are the most common breeding species among farmed cervids in Poland. Monitoring the animals' health, nutritional status, and welfare are highly important aspects in their breeding. Haematological variables are important indicators for comparing the physiological status of the animals and for monitoring the changes in the organism related to the adaptation to the breeding conditions. The aim of this study was to assess the impact of the day's length and the total protein content in the diet for the farmed fallow deer on the selected haematological variables. The study demonstrated a significant decline in the mean corpuscular volume (MCV) and an increase of the mean corpuscular haemoglobin concentration (MCHC) (P < 0.05) in all the animals after the winter period. However, the animal group exposed to prolonged daylight exhibited a significant increase in the platelet distribution width (PDW) and platelet large cell ratio (P-LCR) (P < 0.05). In turn, the group receiving a lower amount of protein in the diet was characterised by a significant reduction in the platelet count (PLT) (P < 0.05). Thus, the length of daylight and the protein content of the diet for fallow deer exert a significant impact on several haematological characteristics, which may serve as indicators of an animal's nutritional status and welfare.