NUTRITIONAL PROFILE AND LEAF SURFACE-STRUCTURE OF SOME NATIVE SHRUBS CONSUMED BY SMALL RUMINANTS IN SEMIARID REGIONS OF NORTHEASTERN MEXICO

This study evaluated browse composition of animal diets of range goats and white-tailed deer (Odocoileus virginianus, texanus) grazing in no rtheastern Mexico and some dominant native browse species fi om semiar id Nuevo Leon, Mexico, were studied to determine their nutritional val ue and leaf surface ultrastructure. Browse was the main component of t he annual diets of goats and deer Large differences in nutritional vla ues were found in the different plant species, although all were high in crude protein (range = 12.3-23.5%) and low in cell wall (range = 27 .7-44.7%). Plants such as Acacia rigidula, Acacia berlandieri, Ziziphu s obtusifolia, Porlieria angustifolia, Condalia obovata and Acacia far nesiana showed smooth and waxy leaf surface with the absence of tricho mes. These plants had acceptable digestibility values ranging from 50 to 85%, with exception of Acacia rigidula (31%), probably because of i ts high tannin content. However, this plant was the most prefered for its high abundance in the range. The preference in diets by small rumi nants not only depends on the leaf surface structure, but is highly re lated to the abundance of browse species in the harsh summer season al so as well as their nutritional value. It seems that availability and the high nutritional value of plants had influenced diet selection, al though leaf surface smoothness may play some role in animal selection Besides, leaf surface structure could be an acceptable guide for plant species identification.