Effects of lactic acid bacteria and urea treatment on fermentation quality, digestibility and ruminal fermentation of roll bale rice straw silage in wethers

Abstract

AbstractThe digestibility, nitrogen retention and ruminal fermentation of dry rice straw (DRS), untreated rice straw silage (NRS), lactic acid bacteria (LAB) treated rice straw silage (LRS) and urea treated rice straw silage (URS) were compared in a feeding trial with wethers supplemented with concentrate. Both NRS and LRS provided good fermentation quality although the lactic acid content in LRS was higher than in NRS (P < 0.05). The digestibility of the feed component did not differ among DRS, NRS and LRS treatments; however, the digestibility of crude protein (CP), acid detergent fiber (ADFom), neutral detergent fiber (NDFom) and energy increased in the URS treatment (P < 0.05). With the increase in digestibility, the nutritive values of digestible crude protein (DCP) and digestible energy (DE) also increased in URS treatment (P < 0.05). The high urinary excretion of nitrogen (N) with URS treatment did not influence its improved N retention compared with the other treatments (P < 0.05). The higher ruminal total volatile fatty acid (VFA) and ratio of acetate to propionate (A:P) in ruminal fluid of wethers following URS treatment (P < 0.05) indicated that the urea treatment resulted in effective ruminal fermentation. These results show that although LAB treatment can improve fermentation quality, it had no effect on the digestibility of feed components. Urea was an effective treatment for improving digestibility, N retention and ruminal fermentation.