Effect of feeding feed blocks containing different levels of urea calcium sulphate mixture on feed intake, digestibility and rumen fermentation in Thai native beef cattle fed on rice straw

Four Thai native beef cattle were randomly assigned according to a 4×4 Latin square design to evaluate the effect of urea calcium sulphate mixture (U-cas) levels in feed block on feed intake, apparent digestibility of nutrients and rumen fermentation fed on rice straw based diet. The four dietary treatments were different levels of U-cas supplementation in feed block at 0, 120, 150 and 180g/kg dry matter (DM), respectively. The present results revealed that rice straw intake increased with the increasing levels of U-cas inclusion in the feed block. The highest total intakes of DM and energy (ME, MJ/d) were in cattle receiving feed block containing U-cas at 180g/kg DM, and followed by 150, 120 and 0g/kg DM, respectively. Apparent digestibility of nutrients enhanced the increasing levels of U-cas supplementation in feed blocks, except acid detergent fiber. Rumen pH and temperature were not affected by U-cas levels inclusion in feed block. At 4h post feeding, the concentration of ruminal ammonia nitrogen decreased with increasing levels of U-cas in feed blocks (P