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Individual study: Supplementary feeding of red deer Cervus elaphus reduces winter spruce bark browsing in field enclosures, Slovakia

Published source details

Rajský M., Vodňanský M., Hell P., Slamečka J., Kropil K. & Rajský D. (2008) Influence supplementary feeding on bark browsing by red deer (Cervus elaphus) under experimental conditions. European Journal of Wildlife Research, 54, 701-708


Significant economic loss is caused in some Slovakian forests by large vertebrate herbivores (mainly red deer Cervus elaphus), including via tree damage due to bark browsing. It is generally accepted that supplementary feeding can reduce such damage. Here, the effect of various supplementary feeds on spruce bark browsing intensity in winter was studied in red deer held in outdoor enclosures.

The experiment (December 2006 to March 2007) was undertaken in two periods using the same red deer (15 females, 4-6 years old). In the first period (A), the supplementary feeds were available for 24 h, in the second (B), commencing 21 days later, access to feed was restricted to hours of darkness (17:00-07:00 h); this was to simulate conditions in areas heavily disturbed by hunting in which game animals rest in cover during the day, emerging to graze/browse during the night only. Each period consisted of a 21 day 'preliminary period' (to allow the deer to adjust to the pens and feed), followed by a 10 day 'main period' when feed intake was recorded daily.

The 15 deer were divided into five groups of three, placed in 2,500 m² pens and randomly allocated one of five dietary treatments (feed, and water, available ad libitum):

C - (control) meadow hay only;
GS - meadow hay and grass silage;
MS - meadow hay and maize silage;
MSO - meadow hay and maize silage with oats;
PC - meadow hay and pelleted concentrate.

Each day, fresh spruce (species not given in original paper) stems 200 cm long x 6-20 cm thick were placed in each pen. The amount of browsed bark was estimated.

Average daily spruce bark consumption in the control group in period A was 1,053 g, in the other groups it was very much lower (6 to 20 g). In period B (simulating disturbed hunting areas), bark consumption in all groups increased considerably; the highest increases occured in groups GS (430 vs. 19 g/day) and MS (101 vs. 6 g/day).

In period A, the highest dry matter intake occurred in group MS (2,816 g/day) and the lowest in GS (2,307 g/day). In period B, the highest (2,763 g/day) and the lowest (2,153 g/day) dry matter intake occurred in groups PC and MSO, respectively.

Conclusions: If red deer are provided supplementary food in an attempt to reduce bark browsing, the authors recommend that hay should be combined with maize silage, grass silage or concentrate; results indicate that the deer kept in the enclosures were in fact unable to maintain body weight when meadow hay was the sole supplemental food. The study also indicates that bark browsing may increase considerably if deer are prevented from feeding during the day.

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