Abstract: Spirulina polypeptide is a peptide molecule extracted from Spirulina， a blue-green algae. Because it contains a large amount of proteins， vitamins， minerals， antioxidants and various amino acids， it might significantly improve the antioxidant activity and fermentation quality of alfalfa silage. This study revealed the effects of adding different concentrations of Spirulina peptides on alfalfa silage quality and bacterial community. The experiment was conducted using alfalfa as raw material， and the amount of Spirulina peptide additives was set up with three gradients of 1%， 3%， and 5%， respectively， three replicates were set up for each group， and the 0% amount of additives was as the control group （CK group）. The fermentation was kept at room temperature and protected from light， and the nutrient composition， fermentation quality and bacterial community were determined after 60 days of natural fermentation. The results showed that adding Spirulina polypeptide increased the contents of dry matter （DM）， crude protein （CP）， water soluble carbohydrates（WSC）， and the content of lactic acid （Lactic acid，LA） from 2.22 g·kg^-1 in the control group to 5.67 g·kg^-1， and also reduced the contents of pH， butyric acid （BA） and ammonia nitrogen （NH₃-N）， and improved fermentation quality. The application of spirulina polypeptides broadened the kinds of additives for alfalfa silage.

Key words: Spirulina peptide, Alfalfa silage, Fermentation quality

摘要： 螺旋藻多肽是从螺旋藻（一种蓝绿色藻类）中提取的多肽分子。因其含有大量的蛋白质、维生素、矿物质、抗氧化剂和多种氨基酸，可能显著提高紫花苜蓿（Medicago sativa L.）青贮饲料的抗氧化活性和发酵品质。本研究揭示了添加不同浓度螺旋藻多肽对紫花苜蓿青贮品质、细菌群落的影响，试验以初花期紫花苜蓿为原料，设置螺旋藻多肽添加剂量设3个梯度，分别为1%，3%，5%，每组设3个重复，以添加量为0%作对照组（CK组）。避光室温保存，自然发酵60 d后进行营养成分、发酵品质、细菌群落的测定。结果表明：添加螺旋藻多肽能提升干物质（Dry matter，DM）、粗蛋白（Crude protein，CP）和可溶性碳水化合物（Water-soluble carbohydrates，WSC）含量，提高乳酸（Lactic acid，LA）含量，LA含量由对照组的2.22 g·kg^-1提升至5.67 g·kg^-1，还可降低酸碱度（Pouvoir hydrogene，pH）、丁酸（Butyric acid，BA）和氨态氮（Ammonia nitrogen，NH₃-N）含量，改善发酵品质。螺旋藻多肽的应用拓宽了紫花苜蓿青贮添加剂的种类。

关键词: 螺旋藻多肽, 紫花苜蓿青贮饲料, 发酵品质