Effects of replacing soybean meal with dried rumen digesta on feed intake, digestibility of nutrients, rumen fermentation and nitrogen use efficiency in Thai cattle fed on rice straw

This study assessed the feed intake, nutrient intake, apparent digestibility of nutrient, rumen fermentation and nitrogen utilization of beef cattle fed with different soybean meal (SBM) replacement levels with dried rumen digesta (DRD) at 0, 33, 67 and 100%. Four 1.5-year-old Thai native beef cattle steers with initial body weight (BW±SD) of 92.1±4.59 kg were used in a 4×4 Latin square design. All animals were fed rice straw ad libitum while additional concentrate was fed at 0.5% BW daily. Replacement of DRD for SBM were not altered (P>0.05) on total DM intake while the intake of rice straw of the 100% DRD diet was higher than that of the other diets, and it significantly increased with increase in the replacement level of SBM with DRD (P<0.05). Intakes of organic matter (OM), crude protein (CP), neutral detergent fiber (aNDF) and acid detergent fiber (ADF), digestible organic matter intake, digestible organic matter fermented in the rumen and metabolizable energy showed no difference when compared to those on the control diet (P>0.05). The experimental diets has no effect (P>0.05) on the apparent digestibilities of DM, OM, CP and ADF while aNDF digestibility increased with an increase of DRD in the diet and was highest when inclusion of 100% DRD. No differences (P>0.05) were found in ammonia nitrogen concentration, total volatile fatty acid (VFA) and VFAs profiles in the rumen fluid of cattle fed with DRD when compared to those on control diet. Similarly, N use efficiencies were not altered with level of DRD in the diet. Based on this study, it could be concluded that replacement of SBM by DRD as feed ingredient in cattle diets up to 100% dietary level resulted in improved rice straw intake and aNDF digestibility in beef cattle, without affecting the rumen fermentation or nitrogen use efficiency.