SELECTION OF DIETS BY DUAL-PURPOSE MAMBER GOATS IN MEDITERRANEAN WOODLAND

The feeding behaviour of Mamber dairy goats grazing on Mediterranean w oodland in the Upper Galilee mountains of Israel was studied throughou t a year (1991/92). The percentages of crude protein (CP), neutral det ergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) and condensed tannins (CT) were determined in samples collected by hand to simulate the plant parts selected by the goats. Total feed intake was evaluated by using Cr-sesquioxide as an external marker to determine the amount of faeces excreted, and 48 h in sacco degradabili ty to assess the digestibility of samples. Overall, more time was spen t by goats in feeding on ligneous material (tree and shrub foliage) th an herbaceous vegetation (60 and 40 % of total feeding time, respectiv ely, P < 0.05). The main ligneous species consumed by the goats were Q uercus calliprinos, Sarcopoterium spinosum and Calicotome villosa (20, 13 and 7% of total grazing time, respectively). There was considerabl e variability in the 48 h dry matter (DM) in sacco degradability, and in the concentration of CP, NDF, ADF, ADL and CT, within and between s easons and plant species. Although requirements for nutrients varied a ccording to the physiological stage of the goats, 48 h in sacco DM deg radability and the concentration of non-ADF linked (available) CP, NDF , ADF, ADL and CT in the diet did not vary greatly: respective ranges were 45.0-49.4; 9-12.5; 44-53; 33-39; 12-17 and 3.5-4.7%. It is conclu ded that Mamber goats (i) may not select the best quality diet availab le, but may avoid wide variations in nutrient content of their diets t hroughout the year; and (ii) may not select a diet consistent with max imization of milk yield, but rather with optimization of body conditio n at the onset of the mating season.