Influence of woody plant cover on dietary selection by goats in an Acacia senegal savanna of East Africa

Abstract

Seasonal effects of woody plant cover on dietary selection and nutrition of goats were evaluated in an Acacia senegal savanna in Kenya during the dry season and wet season in 1982. Treatment paddocks were established in light, moderate, and heavy woody plant densities with 13, 31 and 47% total canopy cover, respectively. Grass and grasslike species, particularly Cenchrus ciliaris, Sporobolus pellucides, Eragrostis caespitosa, Digitaria macroblepharia and Chloris roxburghiana dominated goat diets in the early dry season. Browse, particularly Solanum incanum, Grewia bicolor, Acacia mellifera, Acacia senegal and Commiphora africana, were abundant in the diets of goats from August through November in the moderate and heavy woody covered paddocks. Acacia senegal pods were the major source of feed for goats in July and August. Crude protein concentration exceeded requirements of goats throughout the period of study. Organic matter digestibility of the goat diets was lowest in moderate and heavy woody plant conditions in the late dry season. When contemplating bush removal of woody plants (e.g. for tsetse fly control), consideration should be given to the role that large Acacia trees can play in stabilizing protein intake of goats and other domestic or wild browsers. By allowing goats simultaneous access to protein-rich, pod-producing areas and also high caloric grassland areas, pastoralists can diversify diet selection and stabilize nutrient intake. Cutting large Acacia trees for firewood and charcoal is particularly detrimental to the nutritional ecology of goats and perhaps other browsing herbivores.