Effect of drying time on the feed value and dynamic changes in “Sea Rice” straw

“Sea rice” is a new variety of rice (Oryza sativa) being researched in China. Sea rice straw is a by-product of sea rice and one source of feed roughage to be developed. It is necessary to determine the appropriate drying time to evaluate the feed value based on the dynamic changes occurring in the feed. Comparisons were made between the nutritional components of sea rice straw, rice straw (Oryza sativa), corn straw (Zea mays), peanut vines (Arachis hypogaea) and fountain grass (Pennisetum sinese), and the physical properties, nutrient contents, and quality of sea rice straw were analyzed for the drying times of 1, 7, 15, 30, 45 and 60 days. The results showed that the nutrient content of sea rice straw was the lowest among the forages investigated. The feed value of the different forages was ranked as follows: sea rice straw < rice straw < corn straw < fountain grass < peanut vines. With an increase in drying time, the linear density and shearing force of the sea rice straw as well as the gross energy, crude protein content, and ether extract content decreased; the relative feed value and quality index showed no significant changes; and the grading index showed a significant decrease (P < 0.05). With the extension of drying time, the feed value of sea rice straw dropped significantly. Under a temperature of 35 ℃ and a relative humidity of 78% the suitable natural drying time for sea rice straw, in terms of nutrient content, physical properties, and feed index, is 15 days.