Relationships between nutrition and foraging behavior of free-ranging sheep and goats.

Goats generally tolerate dry season forage conditions in northeastern Brazil's tropical deciduous woodland better than sheep do, but the mechanisms underlying sheep and goat response to wet and dry season conditions are not well understood. We evaluated aspects of nutrition and behavior of free-ranging sheep and goats in this woodland to improve our understanding of these mechanisms. Body weight changes, dietary botanical and chemical composition, and daily activities were measured for sheep and goats that foraged in this woodland during four defined periods of a year. Vegetation available to these animals was also measured. Although there was much less available vegetation during the wet season than during the dry season, body weights and dietary crude protein content of sheep and goats increased during the wet season and decreased during the dry season. During the four periods of the year, weight changes of sheep, and possibly those of goats, were positively related to the content of crude protein in their diets. Foraging times of sheep and goats were generally greater during the dry season than during the wet season and were positively related to available browse and inversely related to dietary crude protein content. Sheep and goats may have foraged longer during the dry periods because they were spending more time searching through the large quantity of low-quality vegetation for dietary items with relatively higher levels of crude protein.

Nutrition of goats as influenced by thinning and clearing of deciduous woodland in northeastern Brazil.

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.

The voluntary forage intake and nutrition of goats and sheep in the semi-arid tropics of northeastern Brazil.

The nutritive value of diets selected by free-ranging goats and sheep, and estimates of forage intake, were obtained during the wet (January to May, 1982) and the dry season (June to December, 1981) in the Brazilian state of Ceara. Esophageally fistulated animals were used to collect dietary samples for nutritive evaluation. Organic matter intake (OMI) was estimated by total fecal collections. Goats selected diets higher in crude protein (CP) than did sheep (16.3 and 15.5%, respectively; P = .03). Contrary to current hypotheses, goats did not generally select diets of higher nutritional quality than did sheep. Sheep diets had lower (P less than .05) levels of lignin and equal (P greater than .1) levels of cell wall fiber compared with goats' diets. No difference in in vitro organic matter digestibility (IVOMD) was found between sheep and goats (P greater than .1), averaging 54%. However, major differences in IVOMD occurred during the wet season, as sheep diets were 4 to 10 digestibility units higher than were goats' diets. This may have been due to problems in using the in vitro procedure for dietary samples high in browse material. The OMI averaged 2.2 and 2.1% of body weight for sheep and goats, respectively (P = .08). Lowest levels of OMI (1.2% for sheep and goats) were noted during the latter portion of the wet season when forage biomass was high but nutrient quality was declining due to maturation. Daily digestible energy (DE) intake (kcal) differed (P = .04) between sheep (1,665.5 +/- 23.7) and goats (1,329.7 +/- 27.5).(ABSTRACT TRUNCATED AT 250 WORDS)