The traditional approach to formulating pig diets is based only on minimizing cost while meeting nutritional requirements and thus does not consider the environmental impacts associated with producing feed ingredients. To reduce the overall environmental impact of pork production, feed ingredients can be considered to formulate environmentally friendly diets. However, their potential effects on pig performance could decrease environmental benefits at the farm gate. The objective of this study was to quantify the effects of such eco-friendly pig diets on nitrogen (N) and energy (E) balances, the components of heat production (HP), and the performance of growing pigs. Digestibility coefficients of dry matter (84.5% vs. 88.2%, P < 0.01) and N (80.4% vs. 86.3%, P < 0.01) were significantly lower for the eco-friendly diet than the Control-diet (a commercial diet used in France). N excretion in feces was significantly higher for the group of pigs fed the eco-friendly diet than for the group fed the Control-diet (9.8 vs. 6.9 g/d, respectively, P = 0.01), while the N retention tended to be lower (27.8 vs. 30.3 g/d, respectively; P = 0.06). The metabolizable E:digestible E ratio did not differ between diets, but total HP was significantly lower for the eco-friendly diet group than for the Control-diet group (1,340 vs. 1,388 kJ/kg body weight0.60/d, respectively, P = 0.03). Using feed ingredients with lower environmental impacts, such as locally produced protein or co-products from wheat processing, is an effective way to decrease the environmental impacts of pig production. However, the nutritional composition of these eco-friendly ingredients could be overestimated, in particular the true digestibility of amino acids. This indicates the need to better estimate and consider the true digestibility of eco-friendly diets to decrease environmental impacts of livestock production without decreasing animal performance.
Keywords: alternative protein sources; environmental impacts; multiobjective formulation; nutritional composition; pig production.
Livestock production is a significant contributor to global environmental change. In pig production, animal feed contributes to 55% to 75% of climate change impacts, 70% to 90% of nonrenewable energy use, and 85% to 100% of land occupation. To reduce the overall environmental impact of pork production, feed ingredients can be considered to formulate environmentally friendly diets. These feeding strategies that minimized environmental impacts contained lower proportions of cereals and oilseeds and a higher proportion of high-protein crops and co-products from wheat processing which have lower impacts. The use of these eco-friendly ingredients could influence performance due to their variability in energy, fiber, or protein contents, with an overestimation of their nutritional composition. Thus, decreasing environmental impacts of livestock production without decreasing animal performance requires better characterizing the ingredients that have lower environmental impacts.
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