9th International Deer Biology Congress

AUTHORS: Andreas König, Technical University of Munich, Wildlife Biology and Management Unit

ABSTRACT: The European roe deer (Capreolus capreolus) is a forest dweller [1] and classified as a typical “Browser” or “Concentrate Selector” [2]. This means that roe deer depend on a diet with a low fiber content and high proportion of crude protein [2,3,4]. This is why some hypothesize that roe deer are unable to digest agricultural plants, as these contain a relatively high proportion of fiber [5,6,7].

From 2011 to 2014, the rumena of 220 roe deer and data on the respective conditions were collected from legal hunts in both a forest habitat and in an agricultural habitat [8]. In order to observe seasonal influences, we gathered samples throughout all 12 months of each year. We thus acquired a permit from the local hunting authorities to collect roe deer outside the regular hunting seasons. Our aim was to measure the quality and energy content of the natural roe deer diet (in terms of metabolizable energy (ME)) found in the rumena. We used standard methods of dietary analysis; in vitro ruminal fermentation, crude nutrient analysis, and analysis of neutral/acid detergent fiber and acid detergent lignin [9, 10]. For an overview of the total energy budget of the roe deer, we used a wildlife systems approach to analyze the condition and physiological adaption of roe deer to local and seasonal changes in diet. In addition, the availability and quality of the local vegetation and stress of the deer were evaluated as a measure of human disturbance.

Figure 1: Mean energy concentration (ME MJ / kg DM) in roe deer diets in two different habitats

Roe deer diets in the agricultural habitat had a mean energy content of 6.3 ME MJ/ kg DM, which was significantly more metabolizable energy than was available to roe deer in the forest habitat, where the mean was 5.4 ME MJ/kg DM (Fig. 1). To compensate for the lower energy content, rumen contents of roe deer from the forest habitat was on average 300g heavier than that of deer from the agricultural habitat. Roe deer in the natural forest habitat thus compensate for the lower energy density of the vegetation with a higher intake and increased rumen capacity. According to literature, roe deer need an average energy intake of 3.5 to 5 (10) ME MJ/day [9,11, 12]. With our data we calculated a yearly average energy value between 8 ME MJ / day and 11 ME MJ / day for both populations, and on average both populations gathered the same average energy intake per year. However, in both habitats the proportion of fiber was not less than 21% of dry matter and in winter, roe deer were able to extract more energy from the fibrous diet than domestic sheep, a grazer.

During our study period we did not observe any energy gap between the two populations. In neither of the two areas was supplemental feeding necessary for the roe deer to survive the winter. In terms of dietary energy, the roe deer in agricultural habitat did not notice that it was winter. In general, the roe deer’s microbiome is adaptable to the local vegetation, permitting the animal to exploit energy from plants throughout the year, even with a high proportion of fiber.