Assessing environmental consequences of using co-products in animal feed

Abstract

Purpose:The livestock sector has a major impact on the environment. This environmental impact may be reduced by feeding agricultural co-products (e.g. beet tails) to livestock, as this transforms inedible products for humans into edible products, e.g. pork or beef. Nevertheless, co-products have different applications such as bio-energy production. Based on a framework we developed, we assessed environmental consequences of using co-products in diets of livestock, including the alternative application of that co-product. Method: We performed a consequential life cycle assessment, regarding greenhouse gas emissions (including emissions related to land use change) and land use, for two case studies. Case 1: Increasing the use of wheat middlings in diets of dairy cattle at the expense of using it in diets of pigs. The decreased use of wheat middlings in diets of pigs was substituted with barley, the marginal product. Case 2: Increasing the use of beet tails in diets of dairy cattle at the expense of using it to produce bio-energy. During the production of biogas, electricity, heat, and digestate (that is used as organic fertiliser) were produced. The decrease of electricity and heat was substituted with fossil fuel, and digestate was substituted with artificial fertiliser. Results and discussion: Using wheat middlings in diets of dairy cattle instead of using it in diets of pigs resulted in a reduction of 329 kg CO2-eq per ton wheat middlings and a decrease of 169 m 2 land. Using beet tails in diets of dairy cattle instead of using it as a substrate for anaerobic digestion resulted in a decrease of 239 kg CO2-eq per ton beet tails and a decrease of 154 m 2 land. Emissions regarding land use change contributed significantly in both cases but had a high uncertainty factor, ±170 ton CO2 ha -1 . Excluding emissions 2 from land use change resulted in a decrease of 9 kg CO2 for case 1 'wheat middlings' and an increase of 50 kg CO2-eq for case 2 'beet tails'. Conclusion: Assessing the use of co-products in the livestock sector is of importance because shifting its application, can reduce the environmental impact of the livestock sector. A correct assessment of the environmental consequences of using co-products in animal feed should also include potential changes in impacts outside the livestock sector, such as the impact in the bio-energy sector.

Environmental and health impacts of using food waste as animal feed: a comparative analysis of food waste management options

“…Land use change emissions are the largest source of greenhouse gas emissions associated with certain forms of animal feed, notably soybean meal (van Middelaar et al., 2013), yet are ignored in much of the literature on food waste disposal technologies (but see Tufvesson et al., 2013, van Zanten et al., 2014). In this study, we therefore used the most recent data available on land use change emissions for soybean meal (Nemecek et al., 2014), a major constituent of EU pig feed.…”

“…For this reason, wet food waste feed, or “swill”, has long been a favoured pig feed for smallholder farmers (Westendorf, 2000). Most industrial pig farms in the UK currently use dried feeds; wet feeding is more common in other EU nations, such as the Netherlands, where it is favoured because it permits the use of wet agricultural wastes, such as distillery wastes or beet tails (van Zanten et al., 2014), and because of reported nutritional benefits of wet feeding (Brooks et al., 2001, Missotten et al., 2015). …”

“…(2016) suggest that if the EU were to recycle food waste as pig feed at similar rates to nations such as Japan and South Korea, this would provide enough feed to support 20% of EU pork production, reducing the land use of EU pork by 1.8 million hectares of farmland. Four European studies have evaluated environmental impacts beyond land use, though these considered only manufacturing or retail food wastes or agricultural co-products (such as beet tails or soybean meal) (Tufvesson et al., 2013, Vandermeersch et al., 2014, van Zanten et al., 2014, Eriksson et al., 2015). These studies each adopted a bottom-up life cycle assessment approach and therefore have several inherent drawbacks that lead to system incompleteness and underestimate environmental impacts (Bernstad and la Cour Jansen, 2012, Laurent et al., 2014a, Laurent et al., 2014b).…”

Attributional versus consequential life cycle assessment and feed optimization: alternative protein sources in pig diets

“…Co-products can already have applications, resulting in shifting the application of the co-product from one sector to another sector. To assess the environmental consequences of using co-products in livestock feed, we used a framework developed by Van Zanten et al (2014). Based on this framework, the net environmental impact can be calculated.…”

Influence of Substrate Composition on Beta-Glucans Production and Growth of Ganoderma lucidum

“…The use of residues in mushroom production represents a valuable conversion of low nutritive phytomass into enriched food and also an alternative to minimize environmental impact that may be caused by the incorrect discard (Smil, 1999, Van Zanten et al, 2014. Therefore, growth of G. lucidum, as well as its yield and concentration of β-glucans in soybean hulls, soybean residue and corn residue were analysed considering their nutritional composition, in order to determine which would be the most feasible to be used as supplement in animal feeding.…”