Spent coffee grounds (SCG), a by-product rich in polyphenols, can form part of enteric CH4 mitigation strategies while promoting the circular economy. This study aimed to evaluate the effect of 3 levels of SCG inclusion in the concentrate on enteric CH4 production, feed intake, apparent digestibility, ruminal fermentation pattern, microbial protein supply and gene expression of immune and antioxidant markers in peripheral blood of dry dairy ewes. In a replicated 4 × 4 Latin square design, 8 non-productive Latxa ewes were assigned to a concentrate that differed in the level of SCG: Control (0 g/kg DM), SCG100 (100 g/kg DM), SCG150 (150 g/kg DM) and SCG200 (200 g/kg DM). In each period, 14 days of adaptation were allowed, followed by 7 days in individual metabolic cages, and 3 days in respiratory chambers. To avoid a carry-over effect a minimum of 7 days were allotted between periods in which ewes consumed control concentrate and grass hay. Total organic matter intake (OMI) and CH4 emissions (g/d) presented a quadratic response (P=0.008 and P<0.001, respectively) to increasing levels of SCG in the feed. However, when CH4 emissions were corrected for OMI, a linear decrease was observed with increasing levels of SCG in the concentrate (P=0.009). This reduction in CH4 emissions (g/kg OMI) could be explained by the linear decrease (P=0.034) observed in apparent digestibility of organic matter (OM), particularly in crude protein (CP) and starch (P=0.002 and P=0.003, respectively), with increasing levels of SCG in the concentrate. No significant response was found on CH4 emissions corrected for digestible OM and on ruminal fermentation pattern. Regarding microbial protein supply, a linear increase in microbial protein supply efficiency (P=0.008) was observed with increasing levels of SCG in the concentrate. Moreover, SCG inclusion linearly reduced interleukin 10 (P=0.031), nuclear factor E2-related factor 2 (P=0.007), nuclear factor kappa β (P=0.014), superoxide dismutase 1 (P=0.015) gene expression and tended to linearly reduce those of tumor necrosis factor-α (P=0.074) and glutathione peroxidase 1 (P=0.082). In conclusion, inclusion of SCG up to 200 g/kg in the concentrate did not modify ruminal fermentation pattern, but linearly reduced CH4 emissions per kg of OMI, due to a linear decrease in apparent digestibility of CP and starch. Moreover, linearly increased the efficiency of microbial supply and improved sheep’s blood antioxidant-immune status.

中文翻译：

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用过的咖啡渣对 Latxa 绵羊摄入量、表观消化率、发酵模式、甲烷排放、微生物蛋白供应和抗氧化状态的剂量依赖性影响


废咖啡渣 （SCG） 是一种富含多酚的副产品，可以成为肠道 CH4 缓解策略的一部分，同时促进循环经济。本研究旨在评价浓缩物中 3 个水平的 SCG 掺杂物对干奶母羊外周血肠道 CH4 产生、采食量、表观消化率、瘤胃发酵模式、微生物蛋白供应以及免疫和抗氧化标志物基因表达的影响。在重复的 4 × 4 拉丁方设计中，将 8 只非生产性 Latxa 母羊分配到 SCG 水平不同的浓缩物中：对照（0 g/kg DM）、SCG100（100 g/kg DM）、SCG150（150 g/kg DM）和 SCG200（200 g/kg DM）。在每个时期，允许 14 天的适应，然后是在单个代谢笼中 7 天，在呼吸室中 3 天。为避免结转效应，在母羊食用对照精料和草干草的期间之间至少分配 7 天。总有机质摄入量 （OMI） 和 CH4 排放 （g/d） 对饲料中 SCG 水平的增加呈二次响应 （分别为 P=0.008 和 P<0.001）。然而，当针对 OMI 校正 CH4 排放时，观察到随着精矿中 SCG 水平的增加而线性降低 （P=0.009）。CH4 排放量 （g/kg OMI） 的减少可以用有机物 （OM） 的表观消化率线性降低 （P=0.034） 来解释，特别是粗蛋白 （CP） 和淀粉 （P=0.002 和 P=0.003），随着浓缩物中 SCG 水平的增加。在校正为可消化 OM 的 CH4 排放和瘤胃发酵模式上未发现显著响应。关于微生物蛋白供应，微生物蛋白供应效率呈线性增加 （P=0.008） 中观察到浓缩物中 SCG 水平增加。此外，SCG 包涵体线性降低白细胞介素 10 （P=0.031） 、核因子 E2 相关因子 2 （P=0.007）、核因子 kappa β （P=0.014） 、超氧化物歧化酶 1 （P=0.015） 基因表达，并趋于线性降低肿瘤坏死因子 α （P=0.074） 和谷胱甘肽过氧化物酶 1 （P=0.082）。总之，在浓缩物中加入高达 200 g/kg 的 SCG 不会改变瘤胃发酵模式，但由于 CP 和淀粉的表观消化率线性降低，每公斤 OMI 的 CH4 排放量呈线性降低。此外，线性提高了微生物供应的效率并改善了羊血的抗氧化免疫状态。