Abstract The increasing demand for animal protein by the growing world population intensifies the exploration of novel feed sources. This study evaluated the nutritional value of six intact seaweed species (i.e. the brown species Saccharina latissima, Laminaria digitata, and Ascophyllum nodossum, the red species Palmaria palmata, and Chondrus crispus and green species Ulva lactuca), collected from the coast of Ireland, Scotland and France as an ingredient for animal feed. The nutrient composition, in vitro digestibility, and in vitro gas production simulating rumen fermentation, were determined. The nutrient contents (g/kg dry matter), both between and within species, were highly variable, ranging from 45–248 for crude protein, 351–691 for non-starch polysaccharides, and 173–445 for ash. Overall, the brown seaweeds had the highest non-starch polysaccharides content, whereas samples of the red and green seaweeds had an amino acid content up to 265 g/kg dry matter. All samples had a substantial non-protein nitrogen fraction, varying from 0.12–0.29 of nitrogen. The fibre fractions of brown seaweeds showed different properties than land-based plants, as illustrated by a lower analysed neutral detergent fibre than acid detergent fibre content. The ileal organic matter and nitrogen digestibility, as well as the total tract organic matter digestibility (mean digestibility coefficients: 0.81, 0.89 and 0.88, respectively) were lower for all seaweeds compared to soybean meal (digestibility coefficients: 0.84, 0.98 and 0.97, respectively). S. latissima, L digitata, P. palmata and U. lactuca had a higher maximum gas production than alfalfa, but lower than sugar beet pulp. Based on the protein content and amino acid-pattern, intact P. palmata and U. lactuca would be a valuable protein source for farm animals, with the high non-starch polysaccharides and non-protein nitrogen contents and a low in vitro digestibility potentially limiting their use as a feed ingredient for monogastric species. The fermentability of L. digitata, S. latissima and P. palmata indicate that these intact seaweeds may have a higher nutritional value in ruminants. The high ash content in all seaweed species hampers the use of intact seaweed for both ruminants and monogastrics. Extraction of protein and other favourable components, while reducing the ash content, seems an important step towards seaweed inclusion in animal diets. Further identification and characterisation of seaweed polysaccharides is required to understand and improve the digestibility of seaweed fractions.

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评估欧洲西北部海域海藻在动物营养中的应用

摘要 不断增长的世界人口对动物蛋白的需求不断增加，这加剧了对新型饲料来源的探索。本研究评估了从爱尔兰、苏格兰海岸采集的 6 种完整海藻（即棕色种 Saccharina latissima、Laminaria digitata 和 Ascophyllum nodossum，红色种 Palmaria palmata、Chondrus discus 和绿色种 Ulva lactuca）的营养价值和法国作为动物饲料的成分。测定了模拟瘤胃发酵的营养成分、体外消化率和体外产气量。物种之间和物种内的营养成分（g/kg 干物质）变化很大，粗蛋白为 45-248，非淀粉多糖为 351-691，灰分为 173-445。全面的，棕色海藻的非淀粉多糖含量最高，而红色和绿色海藻样品的氨基酸含量高达 265 g/kg 干物质。所有样品都含有大量的非蛋白氮成分，从 0.12-0.29 的氮变化。棕色海藻的纤维部分显示出与陆基植物不同的特性，如分析的中性洗涤纤维含量低于酸性洗涤纤维含量所示。与豆粕相比，所有海藻的回肠有机质和氮消化率以及全道有机质消化率（平均消化率系数分别为 0.81、0.89 和 0.88）均低于豆粕（消化率系数分别为 0.84、0.98 和 0.97） ）。S. latissima、L digitata、P. palmata 和 U. lactuca 的最大产气量高于苜蓿，但低于甜菜浆。根据蛋白质含量和氨基酸模式，完整的掌叶松和莴苣将是农场动物的宝贵蛋白质来源，其非淀粉多糖和非蛋白氮含量高，体外消化率低，可能会限制它们用作单胃动物的饲料成分。L. digitata、S. latissima 和 P. palmata 的发酵能力表明这些完整的海藻在反刍动物中可能具有更高的营养价值。所有海藻物种的高灰分含量阻碍了反刍动物和单胃动物使用完整海藻。提取蛋白质和其他有益成分，同时减少灰分含量，似乎是将海藻纳入动物饮食的重要一步。