An approach to including protein quality when assessing the net contribution of livestock to human food supply
An approach to including protein quality when assessing the net contribution of livestock to human food supply
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DOI：
10.1017/s1751731116000902
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发表时间：
2016-11-01
期刊：
影响因子：
3.6
通讯作者：
Zollitsch, W.
中科院分区：
文献类型：
--
作者：
Ertl, P.;Knaus, W.;Zollitsch, W.
从动物来源生产蛋白质经常受到批评，因为将饲料中的植物蛋白转化为动物产品中的蛋白质的效率很低。然而，这一批评没有考虑到这样一个事实，即喂给动物的大部分植物蛋白可能是人类不能食用的，而且动物蛋白的质量通常比植物蛋白更好。因此，本研究的目的是评估通过畜牧业生产将潜在的人类食用植物蛋白转化为动物产品过程中蛋白质质量的变化；以奥地利30个奶牛场的数据为例进行研究。第二个目标是开发一种将这些变化与数量方面相结合的方法(例如，人类可食用饲料转化效率，定义为动物产品中的千克蛋白质除以饲料中潜在的人类可食用蛋白质)。使用蛋白质消化率校正氨基酸评分和可消化必需氨基酸评分来评估潜在人类可食用输入和输出的蛋白质质量，这两种方法是联合国粮食及农业组织提出的描述蛋白质对人类营养价值的两种方法。根据所使用的方法，在谷仓门水平上，动物产品的蛋白质得分比潜在的人类可食用植物蛋白高1.40到1.87倍(=蛋白质质量比(PQR))。将1.87的PQR与相同农场的HEFCE相结合，得到HeFCExPQR为2.15。因此，从数量和质量两方面考虑，供人类食用的动物产品(在这种情况下是牛奶和牛肉)中蛋白质的价值是潜在人类可食用植物蛋白投入中蛋白质的2.15倍。这项研究的结果强调，在评估牲畜对人类食物供应的净贡献时，有必要包括由于植物蛋白向动物蛋白转化而引起的蛋白质质量变化。此外，在选择用于评估不同蛋白质生产的环境影响的功能单位时，可能还需要考虑蛋白质质量的这些差异。
The production of protein from animal sources is often criticized because of the low efficiency of converting plant protein from feeds into protein in the animal products. However, this critique does not consider the fact that large portions of the plant-based proteins fed to animals may be human-inedible and that the quality of animal proteins is usually superior as compared with plant proteins. The aim of the present study was therefore to assess changes in protein quality in the course of the transformation of potentially human-edible plant proteins into animal products via livestock production; data from 30 Austrian dairy farms were used as a case study. A second aim was to develop an approach for combining these changes with quantitative aspects (e.g. with the human-edible feed conversion efficiency (heFCE), defined as kilogram protein in the animal product divided by kilogram potentially human-edible protein in the feeds). Protein quality of potentially human-edible inputs and outputs was assessed using the protein digestibility-corrected amino acid score and the digestible indispensable amino acid score, two methods proposed by the Food and Agriculture Organization of the United Nations to describe the nutritional value of proteins for humans. Depending on the method used, protein scores were between 1.40 and 1.87 times higher for the animal products than for the potentially human-edible plant protein input on a barn-gate level (=protein quality ratio (PQR)). Combining the PQR of 1.87 with the heFCE for the same farms resulted in heFCExPQR of 2.15. Thus, considering both quantity and quality, the value of the proteins in the animal products for human consumption (in this case in milk and beef) is 2.15 times higher than that of proteins in the potentially human-edible plant protein inputs. The results of this study emphasize the necessity of including protein quality changes resulting from the transformation of plant proteins to animal proteins when evaluating the net contribution of livestock to the human food supply. Furthermore, these differences in protein quality might also need to be considered when choosing a functional unit for the assessment of environmental impacts of the production of different proteins.