This study investigated the effects of feeding clinoptilolite (CLN; 2.5% of diet DM) 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 d 19. Indwelling pH loggers were used to measure ruminal pH from d 15 to 21. Blood was collected 3-h post-feeding on d 21 for metabolite analysis. Fecal grab and urine spot samples were also collected from d 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 (SCFA) 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：

---

不同粒径斜发沸石的饲喂或围栏表面施用：对饲养场牛氮利用率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；日粮 DM 的 2.5%）对瘤胃发酵特性、氮 (N) 利用率和粪便氨氮 (NH3) 的影响饲养场牛的排放。还评估了直接向围栏表面施用 30 或 400 µm CLN（2,250 千克/公顷）对粪便 NH3-N 排放的影响。六头小母牛用于重复 3 × 3 拉丁方设计，周期为 21 天。饮食治疗为：1) 无补充剂的育肥日粮 (CON)，2) CON + 30 µm CLN (CLN-30)，以及 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 天饲喂后 3 小时收集血液用于代谢物分析。还从第 19 天至第 21 天收集粪便和尿液斑点样本，以测量养分消化率、氮排泄途径和体外 NH3 排放。饮食对营养摄入量、表观总消化道消化率、瘤胃短链脂肪酸 (SCFA) 分布和 pH 值没有影响 (P ≥ 0.12)。 CLN-30 的瘤胃 NH3 浓度低于 CON 的小母牛 (P = 0.04)，但 CON 和 CLN-400 小母牛的瘤胃 NH3 浓度没有差异。虽然饮食对血浆尿素氮 (PUN) 浓度没有影响 (P = 0.50)，但 CLN-30 的尿素氮排泄比例低于 CON 和 CLN-400 小母牛 (P = 0.01)。 CLN-400 的尿 NH3-N 排泄量高于 CON 的小母牛 (P ≤ 0.04)，但 CLN-30 和 CLN-400 小母牛之间没有差异。饲喂 CLN 还增加 (P ≤ 0.02) 粪便中钾 (K) 和铁 (Fe) 的排泄，并减少 (P = 0.01) 尿液中钙 (Ca) 的排泄。 NH3 排放率存在处理 × 时间交互作用 (P = 0.01)，NH3 排放率在孵化的前 36 小时内最大，并且与 CON 和 CLN-30 小母牛以及围栏表面施用处理相比，CLN-400 粪便的排放率较低。与 CON 和 CLN-30 小母牛以及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)。尽管表面施用效果不佳，但向育肥牛饲喂 400 µm CLN 可能会有益地减少粪便 NH3 排放。然而，在肥育牛日粮中饲喂 CLN 时，需要考虑粪便和尿液中钾和钙等矿物质排泄的变化，这表明生物利用度降低。