Dietary Selection and Nutrition of Spanish Goats as Influenced by Brush Management

Abstract

Botanical composition of Spanish goat diets was only different when diets selected from tebuthiuron-treated pastures were compared to those from untreated and mechanically treated areas in the Texas Post Oak Savannah. However, all brush management treatments significantly affected the browse component in summer diets. Diets selected from untreated and mechanically treated pastures were dominated by browse, while grasses and grasslike plants occurred most in diets selected from the tebuthiuron-treated plots. Yet, during fall and winter, vines comprised the bulk of diets collected on these areas. Forbs were a minor dietary component. Goat diets from untreated and mechanically treated pastures consistently shifted from browse to grasses and grasslike plants as seasons advanced. Selection of grasses and grasslike plants on tebuthiuron-treated pastures declined sharply from summer through winter and increased through spring. Similar but inverse trends occurred in respect to vines and browse. Mean levels of crude protein (CP) in diets selected by esophageally fistulated goats grazing chemically treated pastures were significantly greater than in diets from the other pastures in winter and spring. In summer and fall, dietary forage material from all pastures contained equivalent levels of crude protein. Dietary in vitro digestible organic matter (IVDOM) was higher in summer and winter from tebuthiuron-treated pastures compared to mechanically treated and untreated areas. In fall, diets from tebuthiuron-treated pastures were higher in IVDOM content than those from untreated ones but were similar to diets from mechanically treated pastures. However, in spring all pastures receiving brush management yielded diets with higher IVDOM content than brush-treated areas. In general, methods of brush control had greater effects on IVDOM than on CP contents of diets.