Onderwerp scriptie

A novel approach to assess efficiency of land use by livestock to produce human food - Cindy Klootwijk

The increasing demand for animal-source food will intensify the claim on agricultural land. Land use efficiency, therefore, will be increasingly important for livestock production. The aim of this study, therefore, was to develop a new method to assess efficiency of land use by livestock to produce human food.

The increasing demand for animal-source food will intensify the claim on agricultural land. Land use efficiency, therefore, will be increasingly important for livestock production. Life cycle assessment (LCA) is most commonly used to assess land use efficiency of livestock products. Current LCA studies show that land use per kg of protein is in the same range for eggs and milk. These LCA studies, however, ignore that compared to diets of dairy cattle, diets of laying hens generally contain more plant products that humans could consume directly. Moreover, current LCA studies do not account for the suitability of land to grow human-edible plant products. The aim of this study, therefore, was to develop a new method to assess efficiency of land use by livestock to produce human food. We illustrated our novel approach for the case of Dutch egg and milk production systems.

First, we used a regular LCA to assess land occupation from feed production required to produce one kg of human digestible protein from eggs or milk. Second, all land occupied for feed production was assessed for its potential to directly produce human digestible protein from food crops. Finally, we defined land use efficiency (LUE) as the ratio of the human digestible protein per kilogram of eggs or milk over the potential to directly produce human digestible protein from food crops.

Land occupation for egg production was about 25 m2 per year per kg protein. On this land, about twice as much HE protein can be produced from food crops than from livestock production, resulting in a LUE ratio of about 0.5. For milk production, this ratio strongly depends on the soil type. Dairy farms on peat soils, which are most suitable for cultivation of grass, have a ratio higher than 1, implying efficient land use. Dairy farms on sandy soils, however, have a ratio of about 0.4. Main determinants for land use efficiency were the potential of used land to produce human digestible protein and the efficiency of the livestock species to convert protein in feed into animal-source protein. This novel approach helps to identify livestock systems that could positively contribute to efficient use of land.



Student: CW Klootwijk

Supervisor: dr ir E Mollenhorst

36 Ects