Nutritive Value and Digestibility of Rumex obtusifolius in Three Phenological Stages by Chemical, Nylon Bag and Gas Production Methods

The present study was conducted to identify nutritional value of Rumex obtusifolius in three phenological stages (vegetative growth, flowering, and maturity). Samples were randomly taken in pastures of Saravan in Rasht, Iran in 2015. After drying and grinding, the chemical compositions of Crude Protein (CP), Crude Fiber (CF), Ether Extract (EE), Total Ash (ASH), Neutral Detergent Fiber (NDF), and Acid Detergent Fiber (ADF) were measured based on standard methods. Gas production (in vitro) and Dry Matter (DM) degradability (in sacco) were determined. Phenological stage effects were studied using a completely randomized design in three replications and data were analyzed using SAS software. In phenological stages of the plant with the progress of maturity, the amounts of CP, ASH, Nitrogen Free Extract (NFE), and Non Fibrous Carbohydrates (NFC) decreased while the CF, NDF, and ADF contents increased. CP had the highest value (23.92%) in the vegetative growth and lowest value (6.11%) in maturity stage. The gas production in 96 hours of vegetative growth, flowering, and maturity stages was 37.68, 40.76, and 26.69 ml/0.2g of dry matter. The DM degradability in 96 hours for vegetative growth, flowering, and maturity stages was 80.25, 70.42, and 40.43%, respectively. The correlation coefficient between gas production method and DM degradability methods were 0.99, 0.98, and 0.97 for vegetative growth, flowering, and maturity stages, respectively. Therefore, the gas production method due to its lower cost was suggested for measuring nutritive value of this plant. The results showed that considering higher or equal protein content of this plant during the vegetative growth and flowering stages as compared to alfalfa, it can be used for ruminant animal diet. Using this wild source is possible to significantly decrease the expenses involved in animal nourishment.