Nutrition of Goats as Influenced by Thinning and Clearing of Deciduous Woodland in Northeastern Brazil

Abstract

Nutritive composition of diets and forage intake of goats utilizing pastures of cleared, two levels of thinned (25% and 55% canopy cover) and undisturbed (control) tropical woodland were compared on a seasonal basis. Esophageally fistulated goats were used to collect dietary samples for chemical analysis. Total fecal collections were used to estimate organic matter intake (OMI) and digestible energy intake (DEI). Forage availability during the wet season was more than threefold higher (P less than .1) on treated than on control pastures. Although available forage was similar (P greater than .1) for all treatments by the middle of the dry season, available forage on the control pastures was limited mostly to dry tree leaves. Goats selected diets 4% higher (P less than .1) in neutral detergent fiber on the control pastures than on the treated pastures; otherwise, diets selected by the goats on the various pastures were similar in terms of crude protein, lignin and in vitro organic matter digestibility. However, OMI and DEI were 23 and 31% higher (P less than .1), respectively, on the treated pastures than on the control pastures. There were no differences among the cleared and thinned treatments. Excessively wet conditions during the rainy season adversely affected goat performance. High populations of biting insects and wet field conditions reduced foraging time and diet selection. The generally higher levels of available forage on the cleared and thinned pastures did not result in the goats' selecting diets higher in nutritive value on the treated pastures than on the control pastures. Instead, the increased forage availability for the treated pastures allowed the goats to attain higher intake of forage.