Dietary supplementation of tannic acid modulates nitrogen excretion pattern and urinary nitrogenous constituents of beef cattle

Abstract The objectives of the trial were to investigate the effects of dietary supplementation of tannic acid (TA) on nitrogen (N) excretion pattern and urinary nitrogenous constituents of beef cattle. Four adult Simmental male cattle (initial BW 376.0±9.0 kg) were used as experimental animals. Four levels of TA, i.e. 0, 6.5, 13.0 and 26.0 g/kg dry matter (DM), were added to a basal ration consisted of concentrate mixture and corn silage in a 4×4 Latin square design as experimental treatments, respectively. Each experimental period consisted of a 12-day adaptation phase followed by a 3-day sampling phase. The results showed that supplementing TA did not affect the N retention, but shifted the N excretion from urine to faeces, regulated the urinary N components by decreasing urea and increasing hippuric acid.