Rapid evaluation method for rice (Oryza sativa L.) straw feeding quality

Since conventional methods to evaluate the feeding quality of rice (Oryza sativa L.) straw were time consuming, this study was conducted to investigate the potential of a rapid evaluation method for rice straw feeding quality. Nine rice cultivars in 2011 and ten rice cultivars in 2012 were used in this experiment. The feeding quality related traits (such as nonstructural carbohydrates (NSC), crude protein (CP) and acid detergent fiber (ADF) content, in vitro dry matter digestibility (IVDMD), and the fermentation quality related traits (pH, lactic acid (LA) and NH3-N concentration) of rice straw were analyzed. The fresh top 3rd inter-nodes of stem were used to make freehand sections. The results indicated that the NSC content in the whole plant of rice straw was positively correlated with its IVDMD and the fermentation quality (p < 0.01); the top 3rd node of stem was the main NSC storage organ of rice straw, and the main composition of NSC-starch in this part was also positively correlated with IVDMD and the fermentation quality of the whole plant of rice straw (p < 0.01); the starch particle quantity in the parenchyma area of the top 3rd inter-node was significantly consistent with the starch content in this part. According to the results above, observing the starch particle quantity in the top 3rd inter-node of stem by free hand sections would be a rapid evaluation method for rice straw feeding quality.