This study investigated the effects of feeding clinoptilolite (CLN; 2.5% of diet dry matter) with a particle size of either 30- or 400-µm on ruminal fermentation characteristics, measures of nitrogen (N) utilization, and manure ammonia-N (NH3) emissions in feedlot cattle. The impact of directly applying 30- or 400-µm CLN to the pen surface (2,250 kg/ha) on manure NH3–N emissions was also evaluated. Six beef heifers were used in a replicated 3 × 3 Latin square design with 21-d periods. Dietary treatments were 1) finishing ration with no supplement (CON), 2) CON + 30-µm CLN (CLN-30), and 3) CON + 400-µm CL (CLN-400). Intake was measured daily. To evaluate fermentation characteristics, ruminal fluid was collected on day 19. Indwelling pH loggers were used to measure ruminal pH from days 15 to 21. Blood was collected 3-h post-feeding on day 21 for metabolite analysis. Fecal grab and urine spot samples were also collected from days 19 to 21 to measure nutrient digestibility, route of N excretion, and in vitro NH3 emissions. There was no diet effect (P ≥ 0.12) on nutrient intake and apparent total tract digestibility, and ruminal short-chain fatty acid profile and pH. Ruminal NH3 concentration, which was lower (P = 0.04) for CLN-30 than CON heifers, did not differ between CON and CLN-400 heifers. Although there was no diet effect (P = 0.50) on plasma urea-N (PUN) concentration, proportion of urea-N excreted in urine was lower (P = 0.01) for CLN-30 than CON and CLN-400 heifers. Urinary NH3–N excretion, which was greater (P ≤ 0.04) for CLN-400 than CON heifers, did not differ between CLN-30 and CLN-400 heifers. Feeding CLN also increased (P ≤ 0.02) fecal excretion of potassium (K) and iron (Fe) and reduced (P = 0.01) urinary excretion of calcium (Ca). There was a treatment × time interaction (P = 0.01) for NH3 emission rate, which was greatest within the first 36 h of incubation and was lower for manure from CLN-400 compared to CON and CLN-30 heifers and pen surface application treatments. Cumulative NH3 emissions were lower (P < 0.01) for manure from CLN-400 compared to CON and CLN-30 heifers and the pen surface application treatments. Although surface application was ineffective, feeding 400-µm CLN to finishing cattle could result in a beneficial decrease in manure NH3 emissions. However, changes in fecal and urine excretion of minerals like K and Ca, which suggest a decrease in bioavailability, need to be considered when feeding CLN in finishing cattle diets.

中文翻译：

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不同粒径斜发沸石的饲喂或围栏表面应用：对饲养场牛氮利用和粪便氨排放的影响


本研究调查了饲喂粒径为 30 或 400 μm 的斜发沸石 （CLN;2.5% 的日粮干物质） 对饲养场牛瘤胃发酵特性、氮 （N） 利用率测量和粪便氨氮 （NH3） 排放的影响。还评估了将 30 或 400 μm CLN 直接施用到围栏表面 （2,250 kg/ha） 对粪便 NH3-N 排放的影响。六头肉牛被用于复制的 3 × 3 拉丁方形设计，周期为 21-d。日粮处理为 1） 无补充剂育肥日粮 （CON），2） CON + 30 μm CLN （CLN-30） 和 3） CON + 400 μm CL （CLN-400）。每天测量摄入量。为了评估发酵特性，在第 19 天收集了瘤胃液。使用留置 pH 记录仪测量第 15 至 21 天的瘤胃 pH 值。在第 21 天喂食后 3 小时采集血液用于代谢物分析。还从第 19 天到第 21 天收集了粪便抓取和尿点样本，以测量营养物质消化率、氮排泄途径和体外 NH3 排放。饮食对营养摄入和表观总消化率以及瘤胃短链脂肪酸谱和 pH 值没有影响 （P ≥ 0.12）。CLN-30 的瘤胃 NH3 浓度低于 CON 小母牛 （P = 0.04），CON 和 CLN-400 小母牛之间没有差异。虽然饮食对血浆尿素 N （PUN） 浓度没有影响 （P = 0.50），但 CLN-30 尿液中排泄的尿素 N 比例低于 CON 和 CLN-400 小母牛 （P = 0.01）。CLN-400 的尿 NH3-N 排泄量大于 CON 小母牛 （P ≤ 0.04），CLN-30 和 CLN-400 小母牛之间没有差异。喂养 CLN 还增加了 （P ≤ 0.02） 粪便中钾 （K） 和铁 （Fe） 的排泄，并减少了 （P = 0.01） 钙 （Ca） 的尿液排泄。 NH3 排放率存在处理×时间交互作用 （P = 0.01），与 CON 和 CLN-30 小母牛和猪栏表面施用处理相比，CLN-400 粪便的释放率在孵化的前 36 小时内最大，并且 CLN-400 粪便的排放率较低。与 CON 和 CLN-30 小母牛以及围栏表面施用处理相比，CLN-400 粪便的累积 NH3 排放量较低 （P < 0.01）。虽然表面施用无效，但将 400 μm CLN 饲喂给育肥牛可能会有益地减少粪便 NH3 排放。然而，在育肥牛日粮中饲喂 CLN 时，需要考虑 K 和 Ca 等矿物质的粪便和尿液排泄的变化，这表明生物利用度降低。