Taurine is found in rumen fluid, plasma and urine of beef cattle fed a ration containing sodium sulfate

摘要: Objective: The objectives of the experiment were to study the effects of dietary supplementation with sodium sulfate (Na2SO4) on taurine concentrations of plasma, urine and rumen fluid in steers. Methods: Six Simmental steers (bodyweight 449 ± 19 kg) were used as experimental animals. Three levels of Na2SO4, i.e. 0, 20 and 40 g/d, were added in a basal ration as experimental treatments. The animals and the dietary treatments were randomly allocated in a replicated 3 × 3 Latin square design. Each experimental period included 15 days for adaptation and 5 days for sampling. Rumen fluid, blood and urine were sampled from the steers during each sampling period. Results: Dietary addition with Na2SO4 at 40 g/d increased plasma taurine concentration (P < 0.05) and tended to increase the plasma taurine concentration with increasing Na2SO4 level in a linear manner (P = 0.052). A linear positive regression relationship was found between plasma taurine concentration (µg/mL) and sulfur intake (g/d) (R2 = 0.18, P = 0.046). Taurine was found in rumen fluid and urine. No differences were found in ruminal taurine concentrations or urinary taurine excretions among treatments (P > 0.05). Limitations: We infer that the taurine in rumen fluid should have come from the blood through saliva secretion or/and the rumen microbial synthesis. However, no reports are available on the hypothesis. Further research is needed to investigate the possible origins of ruminal taurine as well as the impacts of taurine on rumen microecosystem and fermentation. Conclusions: Taurine has been found in rumen fluid for the first time in the experiment. Dietary addition with Na2SO4 increased plasma taurine concentrations whereas it did not affect urinary taurine excretions in steers.