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Minimising energy use for crop and animal production to feed a human population - Xiaoyu Han

Several studies show that diets with higher levels of animal protein require more energy than diets with lower levels of animal protein. However, these studies do not account for the competition between food and feed. The objective of this research was to explore the relationship between animal production and energy use when feeding a population. We quantified the energy use of different diet scenarios through an optimization model.

The food sector requires considerable amounts of energy for production of crops and animals, industrial processing, cooking, packaging and transportation. Several studies show that diets with higher levels of animal protein require more energy than diets with lower levels of animal protein. These studies generally quantify energy requirements for pre-defined diets using attributional life cycle assessment. However, these studies do not account for the competition between food and feed. The objective of this research is to explore the relationship between animal production and energy use when feeding a population. We quantified the energy use of different diet scenarios through an optimization model. Diets varied in the percentage of animal protein to total protein (AP %) from 0% to 80% with intervals of 5%. The diets were produced to provide enough dietary energy (2000 kcal/capita/day) and protein (57 gram/capita/day) to the Dutch population (15 million people). We included energy use in crop production, animal production, crop processing, animal processing and cooking. Diets are composed by the model based on the objective function to minimize energy use. We included seven feed and food crops, i.e. wheat, potato, sugar beet, beans, rapeseed, silage maize and grass. Crops were cultivated in 1-6 years rotations. We included two types of animal productions, i.e. dairy cattle and pigs. Pig and dairy production were modelled based on animal production units. The results show that energy requirement remained relatively stable for all diets. In the range between 0-30% AP, energy requirements were slightly reduced because animals use crop by-products that cannot be consumed by humans. Energy requirements for animal production and industrial processing of crops and animals increased along with the increase of AP% in the diet. However, the energy required for cooking decreased because arable products that require relatively much energy for cooking are gradually replaced by industrially processed milk. Dairy cattle provided all the animal protein to the diet, which indicates that dairy production is more energy efficient than pig production. We can conclude that diets containing animal protein do not necessarily require more energy than crop-based diets.

Student: X Han

Supervisors: dr R Ripoll Bosch

ir H van Kernebeek

24 Ects