The role of plants containing secondary compounds in sustainable deer farming - a review

Abstract

The productivity and health of farmed deer is improved by substituting perennial ryegrass-based pasture with forages containing condensed tannins (CT) and/or sesquiterpene lactones. Benefits have included improved lactation, growth, trace element status, resilience to internal parasites and reductions in parasite larval development. Forages evaluated for deer include the forage legumes sulla and birdsfoot tref oil, which contain CT, and the herb chicory, which contains both CT and sesquiterpene lactones. Autumn grazing of weaner deer on chicory has shown growth can be increased whilst anthelmintic requirement reduced compared to grazing of perennial ryegrass/ white clover pasture. The importance of secondary compounds relative to other nutritive characteristics of alternative forage species, such as low fibre and highly digestible carbohydrate concentrations, have not been fully characterised, but they are likely to contribute to improved deer health. Unlike sheep and cattle, deer pr oduce salivary proteins that bind CT, allowing them to consume plants containing higher CT concentrations than sheep and cattle. The effect of CT upon the digestion and absorption of protein, which has been determined for other domestic ruminants, needs to be measured in deer fed forage diets, to establish if beneficial effects exist. In vitro work has shown direct inhibitory effects of CT and sesquiterpene lactones extracted from forages on deer internal parasite larvae. The faeces, rumen and abomasal fluid of deer grazing chicory also contained substances reducing the viability of parasite larvae. Alternative plant species such as chicory, birdsfoot trefoil and forage willows containing secondary compounds will play an important role in low chemical sustainable deer farming. Keywords: anthelmintic, Cichorium intybus,condensed tannins, forage, Hedysarum coronarium, internal parasites, protein, red deer