ANIMAL FEED SCIENCE AND TECHNOLOGY ELSEVIER Animal Feed Science and Technology46 (1994) 87-95 Changes in chemical composition and in vitro digestibility of oesophageal fistula and hand plucked forage samples due to drying method and stage of maturity Thomas G. Papachristou*'", Anastasios S. Nastis b "NationalAgricultural Research Foundation, Forest Research Institute of Thessaloniki (Range Management Laboratory), 5 7006 Vassilika, Thessaloniki, Greece bDepartment of Range and Wildlife Science (236), Aristotle Universityof Thessaloniki, 54006 Thessaloniki, Greece (Received 25 February 1993; accepted 24 August 1993) Abstract The preparation method used for forage samples after collection is important when ob- taining their nutritive value with acceptable accuracy and precision. This study was con- ducted to evaluate the effect of oven drying (40°C) or freeze drying on the nutritional components of forage samples collected: ( 1 ) from a shrubland, at monthly intervals through the year; and (2) from woody species at various stages of maturity. Collection occurred both by hand plucking and via oesophageally fistulated goats. The woody species tested were kermes oak (Quercus coccifera L. ), oriental hornbeam (Carpinus orientalis Mill. ), manna ash (Fraxinus ornus L.), oak species (Quercus pubescens Wild.) and rock-rose (Cistus incanus Rchb. ). Oven-dried fistula samples produced artificially increased levels of neutral detergent fibre and lignin, while the in vitro organic matter digestibility was underestimated in comparison with freeze-dried samples during all grazing periods. A sim- ilar pattern was observed for the hand-clipped samples during the rapid growing season, when the moisture content was high while during the remaining periods of the year, no significant differences were detected. For nutritional studies, when samples contain high proportions of moisture, the only acceptable method is freeze drying. *Corresponding author. 0377-8401/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved SSD10377-8401 (93) 00547-9