Effect of a dietary modification for fattening pigs on the environmental performance of commercial pig production in Greece

Investigation of the combined addition of attapulgite clay and benzoic acid in fattening pig diets seems to be reasonable both from a pig performance and environmental point of view. In this research, an in situ experimental procedure was performed in order to investigate the effect of supplementing the conventional diet (CNVD) supplied to the fattening pigs of a commercial pig farm in Greece (based on maize, barley, wheat bran and soybean meal) with 0.4% w/w attapulgite and 0.5% w/w benzoic acid at the expense of maize (ATTBAD diet) on their feed efficiency and growth performance. The results suggested a significant increase (p <= 0.05) in the total weight gain and the slaughter live-weight and a significant decrease (p <= 0.05) in the feed intake and feed conversion ratio per fattening pig when supplied the ATTBAD. These results were further used as an input to a 'cradle-to-farm-gate' environmental Life Cycle Assessment. The functional unit (FU) was 1 kg of sold pig live-weight and the environmental impact categories (EICs) assessed were climate change (CC) and CC from direct land use change, acidification, eutrophication, land use, water use and fossil energy use. The indicators for all EICs were connected with lower potential estimates per FU in the ATTBAD system, suggesting an improvement of the environmental performance when the ATTBAD is supplied to the fattening pigs of the farm. The improvement of intestinal functionality and enzyme activity, an increase in digesta retention time and a drop of digesta pH in the gastrointestinal tract were indicated as possible causes for the improvement in the growth performance of the fattening pigs when supplied the ATTBAD diet, which however need to be confirmed with further research. The contribution analysis highlighted the importance of the decreased feed intake and the increased total weight gain of the fatteners on the improved environmental performance of the ATTBAD system. The reasonable differences between the indicator estimates of this study and relevant literature, the fair data quality which characterizes the compiled life cycle inventory and the results of the performed Monte Carlo simulation, are considered as a good indication of the validity of the received results and further support the argument of the ATTBAD system's improved environmental performance. Therefore, the use of the ATTBAD instead of the CNVD could potentially offer environmental benefits to the studied supply chain. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.