ABSTRACT
Globally, livestock contributes 40% to agricultural GDP, employs more than a billion people and creates livelihoods for more than 1 billion poor. From a nutritional standpoint, livestock contributes about 30% of the protein in human diets globally and more than 50% in developed countries. At the same time livestock contributes 18% of the total global greenhouse gas (GHG) emissions from human sources, requires 30% of land surface and 70% of agricultural land and is an important agent of land degradation, deforestation and nitrogen (N) and phosphorus (P) cause eutrophication in water bodies (Steinfeld et al., 2006). Feed sourcing and feeding is at the very interface where the ‘good’ and the ‘bad’ of livestock production are negotiated (Blümmel et al., 2010). Feed cost and feed conversion efficiencies largely determine the economic performance of livestock. Feed production takes the bulk of water invested in livestock production (Singh et al., 2004), competes with food production through allocation of arable land and restricts organic matter availability for soil health, while inefficient feed conversion contributes to emissions and environmental pollution. However, feedstuffs are not a homogenous group in how they
interact with natural resource use and environment but can be diversified in a number of ways. Diet formulation and animal requirements can be a starting point, classifying feeds into protein, energy and minerals/trace elements/vitamins. These in turn can be grouped into concentrates, basal diets, forages, roughages, supplements and so on with boundaries often fluent. Another way for stratification could be derived from feed sourcing. Some feed resources compete directly with human nutrition, while others do not. Among the latter count grasslands not suitable for crop production, by-products from cropping, the crop residues (straws, stover, haulms), agro by-products (brans, cakes, threshing residues) and brewery, biofuel by-products and so on. By-products are generally associated with smaller negative environmental footprints than primary produce use such as grains since inputs such as water and land are allocated across several products such as grains, bran and straw or oil, cakes and haulms (Blümmel et al., 2009). Feeds that do not directly compete with human nutrition, such as planted forages, do so indirectly by occupying arable land and consuming nutrients and water (Schader et al., 2015), and their negative environmental footprints can be severe. On the other hand, negative environmental footprints relative to a unit of animal sourced food (ASF) are generally inversely associated with the level of intensification which in turn requires quality feedstuffs (Gerber et al., 2013). Choice of feed sourcing and feeding is, therefore, multidimensional, requiring very context-specific trade-off analysis and optimization strategies. A discussion about use and abuse of cereals, legumes and crop residues in rations for dairy cattle will, therefore, have to look not only at the feed-animal interface but also at the natural resource use-feed interface. This chapter will review key elements in trade-off analysis and explore opportunities and limitations to making better use of existing feed resources and of producing more feed biomass of higher fodder quality.
Consumption of ASF is projected to increase substantially in the decades to come (Delgado et al., 1999; Alexandratos and Bruinsma, 2012). Intuitively, rising demand for ASF should increase feed demand and therefore aggravate the negative aspects of livestock production. However, it is important to realize that this increased demand is predicted to happen almost entirely in so-called emerging economies and developing countries where urbanization and rising incomes change food preference towards ASF (Delgado et al., 1999). For example, milk demand in developing countries in the second decade of the twenty-first century is forecast to increase by about 130 000 000 million tonnes (Gerosa and Skoet, 2012). This development is generally welcome by human nutritionist and development practitioners. First, current low ASF consumption in these countries is widely associated with malnutrition and particularly delayed child development (‘stunting’). Second, increased demand for ASF provides market opportunities and income for small holder and even landless livestock keepers, thereby providing pathways out of poverty (Kristjianson, 2009; CGIAR, 2012). In contrast, for developed countries, nutritionists and health experts as well as environmentalists and animal right activists describe a situation of serious overconsumption of ASF, arguing for a strategy of contraction (reduction in ASF consumption in developed countries) and convergence (increased ASF consumption in developing and emerging countries to attain nutritionally recommended levels); see McMichael et al. (2007). Contraction in ASF consumption in the developed world would
