The objective of this experiment was to investigate the effects of inclusion of dragon fruit peel pellet (DFPP) and dietary non-protein nitrogen (NPN) on nutrients digestibility, rumen fermentation efficiency, plasma antioxidant activity, microbial protein synthesis, milk yield and composition in lactating Holstein-Friesian crossbred cows. Four animals were randomly allotted to 4 dietary treatments according to a 2 × 2 factorial arrangement in 4 × 4 Latin square design. The treatments were as follows: 300 g DM of DFPP +100 g of urea (T1), 300 g DM of DFPP + 200 g of urea (T2), 400 g DM of DFPP + 100 g of urea (T3), and 400 g DM of DFPP + 200 g of urea (T4), respectively. The results showed that intake of rice straw was increased (P < 0.01) by the DFPP addition. Including DFPP and urea did not affect (P > 0.05) the NDF and ADF digestibilities, but increased the apparent digestibilities of dry matter, organic matter, and crude protein (P < 0.01). Rumen fermentation process, especially the propionate concentration, was significantly increased by the DFPP levels. The plasma antioxidant activity was increased (P > 0.05) with the addition of DFPP. The DFPP improved (P < 0.01) microbial protein synthesis. The supplementation of DFPP and urea increased (P < 0.05) milk fat, whereas milk yield and 3.5% fat corrected milk were only increased (P < 0.05) by the DFPP supplementation. Based on these results, addition of DFPP at 400 g/animal per day with urea at 100 g/animal per day improved rumen fermentation, plasma antioxidant activity, milk yield and milk fat percentage.

本实验的目的是研究火龙果皮颗粒（DFPP）和日粮非蛋白氮（NPN）的添加对营养物质消化率、瘤胃发酵效率、血浆抗氧化活性、微生物蛋白质合成、产奶量和成分的影响。哺乳期荷斯坦-弗里斯兰杂交奶牛。根据 4 × 4 拉丁方设计中的 2 × 2 因子排列，将四只动物随机分配至 4 种饮食治疗。处理如下：300 g DFPP DM + 100 g 尿素（T1）、300 g DFPP DM + 200 g 尿素（T2）、400 g DFPP DM + 100 g 尿素（T3）和 400分别为 g DM DFPP + 200 g 尿素 (T4)。 结果表明，添加DFPP增加了稻草的摄入量（P < 0.01）。添加DFPP和尿素不影响 NDF和ADF消化率（ P > 0.05），但增加了干物质、有机质和粗蛋白的表观消化率（ P  < 0.01）。DFPP水平显着提高了瘤胃发酵过程，尤其是丙酸浓度。 添加DFPP后血浆抗氧化活性增加（P >0.05）。DFPP 改善了 ( P  < 0.01) 微生物蛋白质合成。补充 DFPP 和尿素增加了 乳脂( P < 0.05)，而 补充 DFPP仅增加了产奶量和 3.5% 脂肪校正奶 ( P < 0.05)。基于这些结果，每天添加 400 克/动物的 DFPP 和每天 100 克/动物的尿素可改善瘤胃发酵、血浆抗氧化活性、产奶量和乳脂百分比。