DISTINCTIVE FEATURES OF THE NUTRITIONAL ECOLOGY OF BROWSING VERSUS GRAZING RUMINANTS

Dietary and nutritional distinctions between browsing and grazing rumi nants are reviewed and related to feeding types identified by Hofmann and Stewart (1972) from the morphology of the digestive tract. African ruminants show a clear distinction in terms of graminoid-dicot propor tions in the dirt, while among ruminants inhabiting temperate regions few exclusive grazers are represented. Among browsers, the duikers (Ce phalophinae) represent a distinct frugi-folivore category. Most browse rs consume a mix of woody plant leaves and shoots and forbs, and inclu de fruits when available. Grazers consume certain pods but not succule nt fruits. The diets of browsers are higher in protein and lower in ce ll wall constituents than those of similar-sized grazers for most of t he year, but metabolizable energy yield may be similar for both feedin g types. Characterizing the staple food types of larger browsers as '' concentrates'' is misleading. Browsers consumed higher levels of tanni ns and Ether allelochemicals than grazers. The fibrous cell walls of g rasses. particularly those with the C-4 photosynthetic pathway, restri ct the effective use of this food type by browsers Grazers are limited in their capacity to cope with the allelochemicals prevalent in dicot s. Large salivary glands producing tannin-complexing secretions seem t ypical of frugi-folivores that may consume substantial amounts of unri pe fruits.