Global food supply: land use efficiency of livestock systems

Abstract

Purpose Livestock already use most global agricultural land, whereas the demand for animal-source food (ASF) is expected to increase. To address the contribution of livestock to global food supply, we need a measure for land use efficiency of livestock systems. Methods Existing measures capture different aspects of the debate about land use efficiency of livestock systems, such as plant productivity and the efficiency of converting feed, especially human-inedible feed, into animal products. So far, the suitability of land for cultivation of food crops has not been accounted for. Our land use ratio (LUR) includes all above-mentioned aspects and yields a realistic insight into land use efficiency of livestock systems. LUR is defined as the maximum amount of human-digestible protein (HDP) derived from food crops on all land used to cultivate feed required to produce 1 kg ASF over the amount of HDP in that 1 kg ASF. We illustrated our concept for three case systems. Results and discussion The LUR for the case of laying hens equaled 2.08, implying that land required to produce 1 kg HDP from laying hens could directly yield 2.08 kg HDP from human food crops. For dairy cows, the LUR was 2.10 when kept on sandy soils and 0.67 when kept on peat soils. The LUR for dairy cows on peat soils was lower compared to cows on sandy soils because land used to grow grass and grass silage for cows on peats was unsuitable for direct production of food crops. A LUR <1.0 is considered efficient in terms of global food supply and implies that animals produce more HDP per square metre than crops. Conclusions Values <1.0 demonstrate that livestock produce HDP more efficiently than crops. Such livestock systems (with a LUR<1.0), therefore, do have a role in future food supply and therefore contribute to food security. Our LUR offers identification of livestock production systems that contribute to global food supply, i.e. systems that value land with low opportunity costs for arable production and/or byproducts from crop cultivation or the food or energy industry.

Opinion paper: The role of livestock in a sustainable diet: a land-use perspective

“…Not necessarily! Grass-based ruminant systems on marginal land, that is, land not suitable for crop production, produce human digestible protein more efficiently than food crops (Van Zanten et al, 2015a). Furthermore, compared with a vegan diet, consumption of a small amount of ASF reduced land use per person when livestock were mainly fed with co-products (Van Kernebeek et al, 2015).…”

Environmental impacts of food consumption and nutrition: where are we and what is next?

“…van Zanten et al (2015) present a method to account for the suitability of land for the cultivation of food crops. The land use ratio (LUR) is defined as the maximum amount of human digestible protein (HDP) derived from food crops on the land used to cultivate the animal feed over the amount of HDP in the animal product.…”

The water and land footprints of meat and milk production and consumption in Kenya: implications for sustainability and food security

“…This will likely also put land footprint analysis at par with water footprint analysis and enable more reliable analyses that use composite indicators of human appropriation of natural resources. Additionally, a land assessment that takes into account the competition between human food production and animal feed production will aid in better attribution of livestock's contribution to food supply (van Zanten et al 2016). …”