Energy intake and nutritional balance of roe deer (Capreolus capreolus) in special Bavarian landscapes in southern Germany

Context: Irrespective of the fact that the European roe deer (Capreolus capreolus) occurs from the Mediterranean to north of the Arctic Circle and is one of the most abundant and widespread species, roe deer are fed in winter in Germany and Austria. Hunters justify the supplementary feeding with the argument that roe deer do not find sufficient high-quality food in our landscape and they would have to starve in winter. Aims: Our aim was to measure the quality and energy content of the browsed roe deer diet (in terms of metabolisable energy, ME) and the daily energy intake by roe deer. Methodology: Between 2017 and 2019, rumenreticula of 629 roe deer were collected from five extreme habitats in Bavaria. Samples were examined by standard methods of dietary analysis, such as in vitro ruminal fermentation, crude nutrient analysis and the analysis of neutral/acid detergent fibre and acid detergent lignin. In addition, data on body condition and age were collected for each roe deer. Key results: The diet consumed by roe deer has an energy density between 5.1 MJ/kg dry matter (DM) and 6.1 MJ/kg DM on average. Crude fibre contents in the diet varied between 20% and 38% DM. Roe deer compensate for lower energy densities in vegetation by consuming more diet. Across all habitats, adult consumed an annual mean of between 10.6 and 12.9 MJ ME/day. Conclusions: Roe deer find sufficient high-energy food in all landscape types. They consume and can utilise raw fibre to the same extent as do red deer or mouflon. Differences in energy density among habitats result from carbohydrate content and are compensated for by more food intake. Energy deficits in roe deer could not be detected in any habitat at any time. Implications: Roe deer do not need supplementary feeding in any habitat. Supplementary feeding leads to browsing damage because of the lack of raw fibre in the feed.