Seasonal Variation of Chemical Composition and Dry Matter Digestibility of Rangelands in Nw Greece

This study was carried out to determine the chemical composition and in vitro dry matter digestibility of grazable material, during the growing season of plants, in three different altitudinal zones, in native rangelands, northwestern Greece. Samples were collected during the period from May to October of the years 2004 and 2005. Sample collection was accomplished by cutting aboveground biomass at a height similar to that grazed by small ruminants. The results showed that herbage production was significantly affected (P<0.001) by sampling year, growing season and altitudinal zone respectively, as well as (P<0.01) by the “month x year” and (P<0.05) “altitude x month” interactions. CP, ash, EE and CF content and IVDMD affected significantly (P<0.01) by both harvest month and altitudinal zone, while there was no significant affection by the sampling year and the interaction between altitude, month and year (except EE which affected (P<0.01) by the “month x year” interaction). Herbage production strongly related (P<0.01) to the altitude (r= +0.247), harvest month (r= -0.479) and CP content (r= -0.274). IVDMD related positively (P<0.01) to CP (r= +0.729), ash (r= +0.369) and EE (r= +0.351) content and negatively to harvest month (r= -0.779) and to CF content (r= -0.663). It was recommended that additional protein sources should be supplied in order to cover the needs of the grazing animals. It is necessary the transhumance of herds from lower to higher altitude for better utilization of rangelands.