Abstract: [Objective] To investigate the effects of a tea polyphenol-taurine compound additive on the growth performance, rumen fermentation parameters, serum biochemical indices, and antioxidant capacity of beef cattle, providing a reference for the application of novel green feed additives in beef cattle production. [Methods] A total of 120 healthy Simmental crossbred beef cattle aged 12 months with similar body weights were selected and randomly assigned to four groups using a completely randomized design, with 3 replicates per group and 10 cattle per replicate. The control group （CON） was fed a basal diet, while experimental groups Ⅰ, Ⅱ, and Ⅲ were fed the basal diet supplemented with 200, 400, and 600 mg/kg of the tea polyphenol-taurine compound additive （at a 1∶1 ratio of tea polyphenol to taurine）, respectively. The trial consisted of a 15-day pre-trial period and a 60-day formal trial period. Initial body weight of the formal trial period was measured at the end of the pre-trial period, and daily feed intake was recorded throughout the formal trial period. At the end of the formal trial, final body weight of the formal trial period was measured; rumen fluid was collected to determine rumen fermentation parameters; and serum was collected to analyze biochemical and antioxidant indices. [Results] Regarding growth performance, compared with the CON group, the average daily gain of cattle in experimental groups Ⅱ and Ⅲ increased significantly （P<0.05）, while the feed-to-gain ratio （F/G） decreased significantly （P<0.05）; no significant differences were observed in all indicators in experimental group I （P>0.05）, compared with the CON group. For rumen fermentation parameters, compared with the CON group, experimental groups Ⅱ and Ⅲ showed significantly higher the contents of acetate, propionate, butyrate, and total volatile fatty acids in the rumen （P<0.05）, while ammonia nitrogen content decreased significantly （P<0.05）, with experimental group Ⅱ showing superior effects to experimental group Ⅲ. In terms of serum biochemical indices, the contents of total protein and albumin in serum exhibited an initial increase followed by a decrease as the additive dosage increased, with experimental group Ⅱ being significantly higher than the other groups （P<0.05） and urea nitrogen content decreased significantly （P<0.05）. Regarding serum antioxidant capacity, compared with the CON group and experimental group Ⅰ, experimental groups Ⅱ and Ⅲ showed significantly increased activities of superoxide dismutase and glutathione peroxidase in serum, and increased total antioxidant capacity in serum （P<0.05）, while malondialdehyde content decreased significantly （P<0.05）; all antioxidant indices in experimental group Ⅱ were superior to those in experimental groups Ⅰ and Ⅲ. [Conclusion] Under the conditions of this experiment, supplementing the basal diet with 400 mg/kg of the tea polyphenol-taurine compound additive （1∶1 ratio） can significantly improve the growth performance of beef cattle, optimize rumen fermentation patterns, and enhance serum biochemical profiles and antioxidant capacity, serving as an efficient and green feed additive suitable for beef cattle production.

Key words: tea polyphenol-taurine compound additive, beef cattle, growth performance, rumen fermentation, serum biochemical indices, antioxidant capacity