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Abstract Traditional feed formulation focuses on minimizing cost while meeting nutritional requirements and does not consider the environmental impacts associated with producing feed ingredients. Incorporating the impacts of feed ingredients into the formulation process has been proposed as a way to mitigate the impacts of pig production. Garcia-Launay et al. (2018) developed a multi-objective (MO) formulation method based on the environmental impacts of feed ingredients calculated by Life Cycle Assessment (LCA). 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 finishing pigs. We compared two different diets: a control diet in accordance with practices in French commercial farms (Control-diet) and an eco-diet formulated with the MO method (Eco-diet). The Eco-diet contained reduced proportion of cereals (50% vs 70%), no oil meals (0% vs 8%) and greater proportions of coproducts (19.5% vs 5%) and protein crops (26% vs 10%) in comparison with the Control-diet. Pietrain x (Large White x Landrace) entire males n = 12; mean body weight (BW) = 81 kg were used in this study (n = 6 per experimental diet). Animals were housed individually in digestible cages equipped for measurement of individual feed and water intake, feeding behavior, and separate collection of feces and urine. All animals were adapted to experimental conditions, diets, and digestible cages during 14 d. After the adaptation period, pigs were housed in climate respiration chambers (one pig in an individual cage per chamber) for 6 d to measure digestibility of nutrients, energy and nitrogen balance, and heat production components calculated according to Labussière et al. (2013). We did not observe any significant effect of the dietary treatment on growth performance of pigs (feed intake, average daily gain, feed conversion ratio or water consumption). The digestibility coefficients of dry matter (DM) and N were not different between the two groups. N excreted in urine was significantly greater for the group of pigs fed the Control-diet than for the group fed the Eco-friendly diet (13.5 vs 11 gּ pig-1ּ d-1, respectively, P = 0.03) with no difference for N excreted in feces between the two groups. N retention was less in the Control-diet group in comparison with the Eco-diet group (28.3 vs 30.4 gּ pig-1ּ d-1, respectively; P = 0.05). The E balance was similar between the two groups. The protein deposition was less in the Control-diet group than the Eco-diet group (177 vs 190 g/d, respectively, P = 0.05). Formulating feeds with adequate net energy, SID amino-acids and protein levels while choosing feed ingredients with least environmental impacts, such as co-products, can be an effective way to decrease environmental impacts of pig production without consequences on animal performances.
Quelen et al. (Sun,) studied this question.