BACKGROUND In Norway, 3 million discarded egg-laying hens are destructed annually, which equals 1500 tons pure hen meat. Due to the slaughter methods used, this raw material is handled as a high-risk waste, while in reality it constitutes a source of valuable components like proteins and lipids. METHODS This study assess different processing methods (thermal treatment, enzymatic hydrolysis and silaging) for utilization of discarded egg-laying hens for the production of ingredients for human consumption and animal feed. The processing methods were evaluated on the basis of quantity and quality of the obtained products. RESULTS Thermal treatment and enzymatic hydrolysis resulted in extraction of good quality lipids from the raw material. The separated oil (50.1-82.3% of the total lipid content in the raw material) was of high quality based on the content of free fatty acids (≤ 1.0%) and total oxidation value (≤ 3.9). Enzymatic hydrolysis also enabled separation of protein in the form of protein hydrolysate. Addition of Protamex and Papain+Bromelain significantly (p ≤ 0.05) increased the protein content (85.1-94.6%) and decreased the lipid content (0.3-1.1%) in the hydrolysate compared to autolysis (protein content: 64.8-72.3%, lipid content: 1.0-2.6%). Silaging increased the protein digestibility (63.2-79.7% compared to 57.3-66.2% for untreated raw material), and thus constitutes a good method for utilizing the protein content of the raw material for animal feed. CONCLUSION The biotechnological processing methods thermal treatment, enzymatic hydrolysis and silaging can be used to increase the utilization of discarded egg-laying hens for production of ingredients for human consumption and animal feed.

中文翻译：

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利用产蛋母鸡（Gallus Gallus Domesticus）生产人类消费和动物饲料的原料。

背景技术在挪威，每年销毁300万只废弃产蛋鸡，相当于1500吨纯母鸡肉。由于采用的屠宰方法，这种原材料被作为高风险废物处理，而实际上它是蛋白质和脂质等有价值成分的来源。方法本研究评估了利用废弃产蛋鸡生产人类消费和动物饲料原料的不同加工方法（热处理、酶水解和青贮）。根据所得产品的数量和质量对加工方法进行评估。结果热处理和酶水解导致从原材料中提取出优质的脂质。分离出的油（占原料总脂含量的50.1-82.3%），从游离脂肪酸含量（≤1.0%）和总氧化值（≤3.9）来看，品质优良。酶水解还能够以蛋白质水解产物的形式分离蛋白质。与自溶相比，添加 Protamex 和木瓜蛋白酶+菠萝蛋白酶显着 (p ≤ 0.05) 增加了水解产物中的蛋白质含量 (85.1-94.6%) 并降低了脂质含量 (0.3-1.1%)（蛋白质含量：64.8-72.3%，脂质含量）含量：1.0-2.6%）。青贮提高了蛋白质消化率（63.2-79.7%，而未经处理的原料为57.3-66.2%），因此构成了将原料中的蛋白质含量用于动物饲料的良好方法。结论热处理、酶解和青贮等生物技术加工方法可提高废弃蛋鸡的利用率，用于生产人类消费和动物饲料原料。