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.