Changes in nutritional quality of herbage botanical components on a mountain side grassland in North-West Greece

The objective was to determine changes in the nutritional quality of the three predominant botanical components (i.e., grasses, legumes, forbs) in the Preveza Prefecture grasslands in North-Western Greece. The study involved collection of herbage samples during the bloom stage from 12 experimental plots located in three altitudinal zones (i.e., lower, middle, and upper) in 2 consecutive years. Samples were manually separated into the three botanical components and analyzed for crude protein (CP), neutral detergent fibre (aNDFom), acid detergent fibre (ADFom), lignin(sa), in vitro dry matter (DM) digestibility (IVDMD), in vitro NDF digestibility (IVNDFD), metabolizable energy (ME) and minerals (i.e., Ca, P, K, Mg). Altitudinal zone strongly affected the nutritive value of grasses, legumes and forbs. Indeed, altitude above sea level was positively correlated with CP, IVDMD and IVNDFD and negatively correlated with fibre contents. We found that the Ca:P ratio exceeded the animal functional disorder threshold, which posed a hazard; a belief amplified by the high K/(Ca + Mg) ratio, which would increase the risk of grass tetany in ruminants that primarily ate grasses in the upper zone.