The objective of this study was to evaluate the effects of isobutyrate supplementations on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in steers. Eight ruminally cannulated Simmental steers were used in a replicated 4 × 4 Latin square experiment. On DM basis, diet consisted of 60% corn stover and 40% concentrate. Dry matter intake (averaged 9 kg/d) was restricted to 90% of ad libitum intake. The four treatment groups received a daily dose of 0 (control), 8.4, 16.8 or 25.2 g isobutyrate per steer. With increasing isobutyrate supplementation total VFA concentration (range 64.2–74.0 mM) was significantly enhanced. The ratio of acetate to propionate (range 2.72–4.25) was also significantly increased due to the increase in actate production and decrease in propionate production. With increasing isobutyrate supplementation the ruminal degradation of NDF from corn stover was improved but the CP degradability of soybean meal was decreased. Furthermore, the isobutyrate supplementation caused a significantly increased urinary excretion of purine derivatives. Similarly, digestibilities of OM, NDF and CP in the total tract were significantly increased. The present results indicate that dietary supplementation with isobutyrate improved rumen fermentation and feed digestion in beef cattle in a dose-dependent manner. According to the conditions of this experiment, the optimum daily dose of isobutyrate was about 16.8 g/animal.

中文翻译：

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异丁酸对肉牛瘤胃发酵、嘌呤衍生物尿排泄和消化率的影响

本研究的目的是评估添加异丁酸对肉牛瘤胃发酵、嘌呤衍生物尿排泄和饲料消化率的影响。在重复的 4 × 4 拉丁方实验中使用了八头瘤胃插管的西门塔尔公牛。在 DM 基础上，饮食由 60% 的玉米秸秆和 40% 的浓缩物组成。干物质摄入量（平均 9 kg/d）被限制为随意摄入量的 90%。四个治疗组每头公牛接受 0（对照）、8.4、16.8 或 25.2 g 异丁酸盐的日剂量。随着异丁酸补充剂的增加，总 VFA 浓度（范围 64.2-74.0 mM）显着提高。由于乙酸盐产量的增加和丙酸盐产量的减少，乙酸盐与丙酸盐的比率（范围 2.72-4.25）也显着增加。随着异丁酸添加量的增加，玉米秸秆中 NDF 的瘤胃降解得到改善，但豆粕的 CP 降解率降低。此外，异丁酸补充剂导致嘌呤衍生物的尿排泄显着增加。同样，总消化道中 OM、NDF 和 CP 的消化率显着增加。目前的结果表明，日粮中添加异丁酸以剂量依赖性方式改善肉牛的瘤胃发酵和饲料消化。根据本实验条件，异丁酸的最佳日剂量约为16.8g/只。异丁酸补充剂导致嘌呤衍生物的尿排泄显着增加。同样，总消化道中 OM、NDF 和 CP 的消化率显着增加。目前的结果表明，日粮中添加异丁酸以剂量依赖性方式改善肉牛的瘤胃发酵和饲料消化。根据本实验条件，异丁酸的最佳日剂量约为16.8g/只。异丁酸补充剂导致嘌呤衍生物的尿排泄显着增加。同样，总消化道中 OM、NDF 和 CP 的消化率显着增加。目前的结果表明，日粮中添加异丁酸以剂量依赖性方式改善肉牛的瘤胃发酵和饲料消化。根据本实验条件，异丁酸的最佳日剂量约为16.8g/只。