Economic optimization of feeding strategy in pig-fattening units with an individual-based model

Economic results of pig farming systems are highly variable and depend on the prices of feed ingredients used toformulate the diets as well as on pig performance and pork price. Thus, feeding strategies in fattening units arecritical factors in the economic outputs of pig production and major levers for improvement. This work aims atimproving the profitability of pig farms by proposing the best compromise between the cost of feeding and theperformance of animals. We rely on an individual-based bioeconomic model, which calculates the average grossmargin per fattened pig and the environmental impacts of the production according to biological traits of each pig,such as feed intake and protein deposition potentials, and the feeding strategy. The objective function maximizesthe average gross margin per pig using an optimization procedure regarding the feeding strategy. The optimizationproblem is solved with an evolutionary algorithm. The behaviour of this process was investigated, in one-phaseand two-phase feeding programs, using two among three feeds A, B, and C, formulated to achieve 110, 90 or 90% of digestible lysine requirements of an average pig at 30, 65 and 120 kg of body weight, respectively. We studied as decision variables the percentage of the two feeds in the blend at each phase and the average live weight of the pen at the end of the first phase. With this optimization strategy, it is possible to optimize simultaneously the feed mixture to be distributed at each phase and the pig weight at feed change. In two-phase feeding program, for the pig population tested, optimal pen average pig weight at diet change was lighter than common practice (50 vs 65 kg), and optimal feed digestible lysine contents amounted 8.5 and 6.3 g/kg in phase 1 and 2, respectively. Further investigations will extend the range of available decision variables and consider multi-objectives optimization to account for environmental impacts