The objective of this study was to determine enteric methane (CH₄) emissions from lactating cows grazing in two prevalent systems, cultivated pasture system (CU) or native pasture system (NA) in the high Andes of Peru. In CU, multiparous Brown Swiss cattle grazed alfalfa and oat pastures and were supplemented daily with 1 kg of concentrate per cow. In NA, primiparous crossbred cows grazed native pastures without supplementation. The same animals were used in the rainy and dry season for both grazing systems. The SF₆ tracer technique was used to measure CH₄ emissions. Faecal excretion was measured using titanium dioxide marker, organic matter digestibility was estimated from faecal crude protein concentration and both parameters were used to calculate daily feed intake. Individual milk yield was recorded and samples analyzed for their composition. Higher organic matter digestibility was observed in CU than NA (660 vs. 612 g/kg OM; P < 0.001) and in rainy than dry season (653 vs. 619 g/kg OM; P < 0.001). For enteric CH₄ emission expressed per unit of organic matter intake (OMI), CU had lower emission than NA (27.3 vs. 34 g/kg OMI; P < 0.001). Cultivated pasture system also presented lower enteric CH₄ emission per digested OMI than NA (41.4 vs. 55.5 g/kg digested OMI; P < 0.001). Despite the above, no differences were observed between systems (P = 0.263; P = 0.34) or seasons (P = 0.058; P = 0.06) on methane yield (MY; g CH₄/kg DMI) or CH₄ conversion factor (Y_m; % GE intake), averaging 24.7 (SE 1.07) and 7.88 (SE 0.34) across all treatments respectively. Intensity of CH₄ emission (grams per unit of energy corrected milk yield) (MI) presented a system × season interaction (P < 0.001), where NA had higher MI than CU (102 vs. 26.9 g/kg ECM; P < 0.001) with higher estimates during the rainy season, but differences between rainy and dry season were much greater for the NA system. In the current experiment, there was a confounding effect of season with stage of lactation, and of grazing system with animal genotype and parity status of the cows, therefore, care must be taken in interpreting these results. Overall, the current results indicate that multiparous lactating cattle grazing on alfalfa and oats pastures have a significantly lesser methane emission per kg of ECM than primiparous lactating cattle grazing on natural pasture in the high Andes of Peru.

这项研究的目的是确定在秘鲁安第斯山高地两种流行系统中的放牧奶牛的肠道甲烷（CH ₄）排放，这两种系统是耕种牧场系统（CU）或天然牧场系统（NA）。在CU，多头棕色瑞士牛在紫花苜蓿和燕麦牧场上放牧，每天每头母牛补充1千克浓缩物。在北美，初生杂种母牛无需补充即可放牧天然牧场。在雨季和旱季，两种放牧系统都使用相同的动物。SF ₆示踪技术用于测量CH ₄排放。使用二氧化钛标记物测量粪便排泄，根据粪便粗蛋白浓度估算有机物消化率，并使用两个参数计算每日采食量。记录单个乳的产量并分析其成分。在CU中，有机物的消化率高于NA（660 vs. 612 g / kg OM； P <0.001），在雨季比旱季（653 vs. 619 g / kg OM； P <0.001）。对于每单位有机质摄入量（OMI）表示的肠CH ₄排放，CU的排放低于NA（27.3对34 g / kg OMI； P <0.001）。耕种的牧场系统还表现出较低的肠内CH ₄每个消化的OMI的排放量均高于NA（41.4对55.5 g / kg消化的OMI； P <0.001）。尽管有上述规定，但在甲烷产量（MY; g CH ₄ / kg DMI）或CH ₄转化因子（Y ）上，系统之间（P = 0.263; P = 0.34）或季节（P = 0.058; P = 0.06）没有发现差异。_m；％GE摄入量），在所有治疗中平均分别为24.7（SE 1.07）和7.88（SE 0.34）。CH _4的强度排放量（每克能量校正牛奶产量的克数）（MI）表示系统×季节交互作用（P <0.001），其中NA的MI高于CU（102 vs. 26.9 g / kg ECM； P <0.001），估计值更高在雨季，但NA系统的雨季和旱季之间的差异要大得多。在当前的实验中，季节与泌乳阶段，放牧系统与动物基因型和母牛的同等状况有着混杂的影响，因此，在解释这些结果时必须谨慎。总体而言，目前的结果表明，在秘鲁安第斯山高地上，在紫花苜蓿和燕麦牧场上放牧的多头泌乳牛每千克ECM的甲烷排放量明显低于在天然牧场上放牧的初生泌乳牛。