Botanical composition of Caatinga rangeland and diets selected by grazing sheep

Abstract

Sheep dietary selection from species-diverse Caatinga rangeland of semi-arid northeastern Brazil has not been docu-mented. This study examined the botanical composition of the available forage and diets of Dorper x Saint Ines ewes on thinned Caatinga over-seeded with Cenchrus ciliaris and Urochloa mosambicensis. Sixty-three species from 23 families, dominated by shrubs and short trees of low forage nutritive value, were identified in the vegetation. The botanical com-position revealed, on average, high presence of 29.2% Malvaceae and 13.0% C. ciliaris. Using the microhistological technique, sheep showed, on average, 59.6% preference for dicotyledons throughout the year. However, selectivity in-dexes indicated, on average, greater selection for Poaceae during the rainy season (1.5) and for dicotyledons in the dry season (1.8) with a year-round aversion for Malvaceae (0.3). These findings suggest that Caatinga vegetation manage-ment should include Malvaceae thinning and greater incorporation of grasses and herbaceous legumes to improve range-land carrying capacity.