Environmental Impact Based on Life Cycle Assessment of Starting Pig Production Receiving Diets with Reduced Crude Protein Content

The objective was to evaluate, through life cycle assessment and with experimental data, the impact of producing starter pigs (from 15 to 30 kg) fed diets with different crude protein (CP) levels. In Trial I (performance), 28 crossbred barrow piglets, with an initial average weight of 15.3 ± 1.15 kg were divided up in a randomized block design with four treatments, seven replications and one animal per experimental unit. In Trial II (nitrogen and phosphorus balance), 20 crossbred barrow piglets with an average weight of 21.4 ± 1.62 kg were divided up in a randomized block design with four treatments, five replications and one animal per experimental unit. Four experimental feeds were evaluated in both essays (19.24, 18.24, 17.24 and 16.24% of CP), meeting the requirements of digestible amino acids through industrial amino acid (IAA) addition. From Trial I and II data, the environmental impact was calculated for global warming potential, acidification potential, eutrophication potential, cumulative energy demand, terrestrial ecotoxicity and land occupation (LO). There was a linear reduction in nitrogen (P=0.001) and phosphorus (P=0.001) intake, as well as nitrogen excretion (P=0.001), with the reduction on dietary CP. Total nitrogen excretion decreased by 0.238 g/d for each 1 g of reduction on daily nitrogen intake, due to lower amino acid deamination and, as consequence, lower urea excretion. However, there was no statistical difference (P>0.10) among experimental treatments for the impact categories. For LO, there was a tendency (P=0.078) to reduce the impact with CP reduction, which was 8% lower in the diet with 16.24% of CP, in comparison with 19.24%. This was due to the lower soybean inclusion and higher maize inclusion in low CP diets, because the LO impact for soybean meal more than twice as high as for maize. Besides that, feed production was the main contributor to LO impact. Dietary CP reduction for piglets from 15 to 30 kg, through IAA supplementation, showed a tendency to reduce the environmental impact under LO in a Brazilian context of pig production.