Response of Forage Characteristics of Rice Straw to UV-B Radiation in Yuanyang Terrace

Purpose To investigate the response of rice straw forage characteristics to UV-B radiation.

Methods In Yuanyang terrace, the local traditional rice variety, Baijiaolaojing, as research material was cultivatedin situ. The effects of UV-B radiation (0, 2.5, 5.0, and 7.5 kJ/m²) on the rice straw growth morphological parameters (plant length, stem diameter and biomass) and the feed chemical quality components (crude fiber, crude fat, coarse ash, crude protein, neutral detergent fiber, acid detergent fiber, starch, soluble sugar and non-protein nitrogen) were studied under field condition. Furthermore, quality nutritional value index of straw (total amount of absorbable nutrients of straw TDN, net energy NE₁, straw dry matter intake DMI, digestible dry matter DDM and relative feed value RFV).

Results The length and stem diameter of rice straw increased and biomass decreased with increase in enhanced UV-B radiation treatment densities; with enhanced UV-B radiation treatments, there were no significant differences in crude protein content, crude fiber content, crude fat content, crude ash content and neutral detergent fiber content of rice straw. Non-protein nitrogen content, starch content and soluble sugar content showed a single peak change. The acid detergent fiber content was the lowest at 2.5 kJ/m² UV-B radiation treatment; the morphology response index, feed quality response index and comprehensive response index were higher with 2.5 and 5.0 kJ/m² UV-B radiation treatments than those with other treatments; the highest nutritional value index of straw TDN, NE₁, DMI, DDM and RFV were the highest with 2.5 kJ/m² UV-B radiation treatment, which were 46.92 g/kg, 5.01 MJ/kg, 1.93 g/kg, 56.05 g/kg and 83.85%, respectively.

Conclusion Appropriate UV-B radiation could improve the forage characteristics of rice straw. The straw characteristics of rice straw is better with UV-B radiation is 2.5 kJ/m².