State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, P. R. China.
J Anim Sci. 2018 Sep 7;96(9):3699-3711. doi: 10.1093/jas/sky252.
Two consecutive trials were carried out to study the effects of dietary CP and adding gallic acid (GA) in basal rations on nitrogen (N) metabolism and nitrous oxide (N2O) emissions from the urine of beef cattle. In Trial I, eight Simmental castrated male cattle with initial liveweight of 310.5 ± 21.5 kg were used as experimental animals. Two levels of dietary CP (113.5 and 150.8 g/kg DM) and two levels of GA (0.0 and 15.2 g/kg DM) were used as experimental treatments in a 2 × 2 reversal design. Two cattle received each treatment in each of two experimental periods. Each experimental period lasted 19 d, of which the first 14 d were for adaptation and the last 5 d were for sampling. In Trial II, the urine samples collected from Trial I were used for measuring N2O-N emissions using static incubation technique. Glass jars containing soil were used as the incubation vessels. Three jars were used for each of the urine samples as replicates and two jars without urine samples were used as blanks. The incubation lasted 15 d, and the daily N2O-N emission from each jar was determined using gas chromatography. The results showed that no effects of interactions were found between dietary CP and GA on the N metabolism of beef cattle and the estimated cattle N2O-N emissions (P > 0.05). Increasing dietary CP from 113.5 to 150.8 g/kg DM increased the excretions of total N, urinary N, and urea (P < 0.001), whereas adding GA at 15.2 g/kg DM in ration did not affect these parameters (P > 0.05). Increasing dietary CP from 113.5 to 150.8 g/kg DM increased the estimated cattle urine N2O-N emissions by 36.8% (without adding GA) and 32.3% (adding GA at 15.2 g/kg DM) (P < 0.01), whereas adding GA at 15.2 g/kg DM in ration decreased the estimated cattle urine N2O-N emissions by 28.5% (dietary CP 113.5 g/kg DM) and 30.9% (dietary CP 150.8 g/kg DM) (P < 0.01). The inhibiting effects of GA on decreasing the N2O-N emissions of urine could have been resulted from the effects of GA metabolites including pyrogallol and resorcinol excreted in urine. Feeding cattle with relatively low dietary CP or adding GA in ration is effective to decrease the N2O-N emissions from the urine patches of beef cattle applied to soil.
进行了两项连续试验，以研究日粮 CP 和基础日粮中添加没食子酸（GA）对肉牛氮（N）代谢和尿液中氧化亚氮（N2O）排放的影响。在试验 I 中，使用 8 头初始体重为 310.5±21.5kg 的西门塔尔去势雄性牛作为实验动物。采用 2 水平日粮 CP（113.5 和 150.8g/kg DM）和 2 水平 GA（0.0 和 15.2g/kg DM）进行 2×2 反转设计作为实验处理。每头牛在每个实验期各接受两种处理。每个实验期持续 19d，其中前 14d 用于适应，最后 5d 用于采样。在试验 II 中，使用静态孵育技术测量从试验 I 中收集的尿液样本中的 N2O-N 排放量。使用含有土壤的玻璃罐作为孵育容器。每个尿液样本使用 3 个罐子作为重复，2 个没有尿液样本的罐子作为空白。孵育持续 15d，每天使用气相色谱法测定每个罐子中的 N2O-N 排放量。结果表明，日粮 CP 和 GA 之间没有发现互作效应对肉牛氮代谢和估计的牛尿 N2O-N 排放的影响（P>0.05）。从 113.5g/kg DM 增加日粮 CP 至 150.8g/kg DM 增加了总氮、尿氮和尿素的排泄量（P<0.001），而在日粮中添加 15.2g/kg DM 的 GA 则不影响这些参数（P>0.05）。从 113.5g/kg DM 增加日粮 CP 至 150.8g/kg DM 使估计的牛尿 N2O-N 排放量增加了 36.8%（不添加 GA）和 32.3%（添加 15.2g/kg DM 的 GA）（P<0.01），而在日粮中添加 15.2g/kg DM 的 GA 使估计的牛尿 N2O-N 排放量降低了 28.5%（日粮 CP 113.5g/kg DM）和 30.9%（日粮 CP 150.8g/kg DM）（P<0.01）。GA 对降低尿 N2O-N 排放的抑制作用可能是由于 GA 代谢物（包括尿中排出的焦儿茶酚和间苯二酚）的作用所致。给牛饲喂相对低蛋白日粮或在日粮中添加 GA 可有效降低施用于土壤的肉牛尿斑中 N2O-N 的排放。
