Effects of dry grassland vegetative cycle on sheep rumen: a key tool for rangeland management

From an ecological viewpoint, the Apennine grasslands show an annual productive trend, with the highest production corresponding to the flowering peak at the end of June. In the summer, the quantity of phytomass available for flock feeding decreases and a forage biochemical alteration occurs because the increase in the lignin percentage, with a consequent reduction of forage digestibility and nutritional supply. Ruminant digestive apparatus shows high degree of structural and functional variability, reached by means of evolutionary steps; Hofmann demonstrated the occurrence of seasonal adaptations of the digestive system in relation to forage availability and climatic conditions. Anatomical researches, supporting eco-vegetational investigations focused on the maintenance of pastoral ecosystem biodiversity demonstrated modifications of the sheep rumen related to the vegetative cycle of pasture and to interannual climatic differences. At rumen level, four indicative regions were monitored: atrium, dorsal and ventral sac, and dorsocaudal blindsac floor. All regions showed modification linked to different stages of pasture vegetative cycle. We observed macroscopic modifications in papillae mean area, which directly affects the Surface Enlargement Factor during the pasture vegetative cycle, also linked to interannual climatic variations. Modifications were observed also at microscopical level as rumen epithelium keratinization degree and calibre and number of blood vessels. Rumen ventral sac was the rumen region showing macro- and microscopical modification mainly related to pasture qualitative and quantitative changes. At the same time, we monitored the animal Body Condition Score (BCS). Obtained results allowed the validation of BCS as representative parameter of morphofunctional modifications, which are strictly related to ecological-productive variations of the grassland systems. The research gave the outputs to provide breeders a simple method for improving farm management and to define the best practices allowing breeders to fulfil European Union aims for biodiversity maintenance through animal husbandry.