An approach to including protein quality when assessing the net contribution of livestock to human food supply

Abstract

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 heFCE × PQR 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.

Land Use for Edible Protein of Animal Origin—A Review

“…Some authors consider a part of the area (20%–50%) used for growing the main product (e.g., cereals, oilseeds) as an area for the co-product. However, in other studies, land use was not considered for growing co-products at all [21,58,101,102]. In accordance with this concept, co-products may replace forage and/or concentrates in the diets without any additional LF as shown in Table 6 in comparison to Table 9.…”

A glimpse of the future in animal nutrition science. 1. Past and future challenges

“…The protein quality of beef and milk is 1.87 greater than the quality of the potentially human-edible protein from feeds. When combined with the human-edible conversion efficiency, animal products for human consumption are 2.15 times greater than plant sources on a protein-equivalent basis (Ertl et al, 2016). This finding places animal products on a much better perspective when comparing their environmental impact and overall contribution to the humankind.…”

Use of house cricket to address food security in Kenya: Nutrient and chitin composition of farmed crickets as influenced by age

“…While the major source of protein for human consumption is plant and animal proteins (meat, pork, fish, milk and eggs) which is rated higher in quality, and therefore preferred by many people (Ertl et al, 2016;Martens et al, 2013;Cook and Monsen, 1976). These animal proteins are however expensive and not easily available (Van Huis, 2013).…”