Reducing environmental impacts of feed using multiobjective formulation: What benefits at the farm gate for pig and broiler production?

Feed production is the main contributor to several environmental impacts of livestock. To decrease environmental impacts of feed, those of feedstuffs should be considered during formulation. In particular, multiobjective feed formulation (MOF) can help reduce several environmental impacts simultaneously while keeping any increase in feed price moderate. The objective of this study was to assess environmental benefits of MOF at the farm gate for fattening pigs and broilers. For pigs, three feeding strategies were tested: classic 2-phase (2P), 2-phase with lower net energy content (2P-), and multiphase (MP). For broilers, two strategies were tested: classic 3-phase (3P) and 3-phase with higher digestible amino acid contents and lower metabolisable energy content (3P+). Diets were formulated using both least-cost formulation (LCF) and MOF, yielding six pig scenarios and four broiler scenarios. Environmental impacts at the farm gate were estimated using a modelling approach based on life cycle assessment. Indicators for six impact categories were then calculated: climate change (CC), cumulative non-renewable energy demand (CEDNR), acidification (AC), eutrophication (EU), land occupation (LO), and phosphorus demand (PD). As expected, MOF had lower farm-gate impacts than LCF (as much as -13%), but the degree of decrease varied by feeding strategy and impact. For pigs, MOF was equally effective in all strategies at reducing PD (-6 to -9%) and AC (-2%). In contrast, MOF was more effective in 2P and 2P- at decreasing CC (-5% to -7%), LO (-9% to -13%) and EU (-6% to -8%) than in MP (CC: -2%; LO: -4%; EU: -3%). The benefit of MOF was found greater in 2P (-7%) than in other pig strategies for CEDNR (-3 to +0%). For broilers, MOF was equally effective in both strategies tested at decreasing PD (-12%), AC (-2%), and EU (-4%). For CC and CEDNR, MOF was more effective in 3P (CC: -9%; CEDNR: -11%) than 3P+ (-6% for both impacts), but not for LO (+3% in 3P vs -1% in 3P+). These differences were due mainly to differences in animal performance (especially feed conversion ratio) among the strategies tested. Finally, in all scenarios, gross margin at the farm gate decreased with MOF comparatively to LCF (pigs: -3% to -11%); broilers: -7% to -11%). These results demonstrate the importance of comprehensive economic and environmental optimisation of feeding strategies by simultaneously considering feed impacts, animal performance, and manure management. To do so, further research is therefore required to develop new modelling tools.

Effect of feeding strategy on environmental impacts of pig fattening in different contexts of production: evaluation through life cycle assessment.

Life cycle assessment (LCA) has been used in many studies to evaluate the effect of feeding strategy on the environmental impact of pig production. However, because most studies have been conducted in European conditions, the question of possible interactions with the context of production is still under debate. The objective of this study was to evaluate these effects in 2 contrasted geographic contexts of production, South America (Brazil) and Europe (France). The LCA considered the process of pig fattening, including production and transport of feed ingredients and feed, raising of fattening pigs, and manure storage, transport, and spreading. Impacts were calculated at the farm gate, and the functional unit considered was 1 kg of BW gain over the fattening period. The performances of pigs were simulated for each scenario using the InraPorc population model (2,000 pigs per scenario considering between-animal variability). The LCA calculations were performed for each pig according to its own performance and excretion, and the results were subjected to variance analysis. The results indicate that for some impacts there are clear interactions between the effects of the feeding program, the origin of soybean, and the location of production. For climate change, interest in phase feeding and incorporation of crystalline AA (CAA) is limited and even counterproductive in Brazil with soybeans from the South (without deforestation), whereas they appear to be efficient strategies with soybeans from the Center West (with deforestation), especially in France. Rather similar effects, as those for climate change, were observed for cumulative energy demand. Conversely, potential eutrophication and acidification impacts were reduced by phase feeding and CAA addition in a rather similar way in all situations. Individual daily feeding, the only strategy that took into account between-animal variability, was the most effective approach for reducing the life cycle impact of pig fattening in all situations, whereas the potential of phase feeding programs and CAA was dependent on soybean origin and the geographical context of pig production, in contrast with previous results.

Sites of nutrient digestion in growing pigs: effect of dietary fiber.

The impact of dietary fiber on fecal digestion is well-known and provides a comprehensive approach toward nutrient digestibility and availability. Little quantitative information is available on digestion of fiber in the different segments of the gastrointestinal tract (GIT). The objectives of this study were to obtain a method allowing the quantification of the digestive process in different segments of the GIT and to study the impact of dietary fiber on nutrient digestibility. Six barrows (average initial BW of 30 kg and fitted with a simple T-cannula at the proximal duodenum and caudal ileum) were used in a replicated 3 x 3 Latin square design. In each period, pigs were offered 1 of 3 diets differing in fiber content (low, medium, and high). Differences in fiber content were created by replacing wheat and barley with wheat bran. Titanium dioxide was included in the diet as an indigestible marker to determine the apparent digestibility coefficients in different segments of the GIT. The apparent digestibility of ash, CP, DM, and OM increased in the different segments of the GIT. Duodenal digestibility coefficients were negative for ash (e.g., -39.9% for the medium- and high-fiber diets), indicating important endogenous mineral secretions by the stomach and digestive glands. The duodenal digestibility of other nutrients and OM were positive but close to zero and numerically lower in the diets with the greater fiber contents. The fiber content in the diet did not affect the apparent ileal digestibility of nutrients. Increasing the fiber content in the diet affected the fecal digestibility of CP, ether extract, and energy (P < 0.01). The method used for studying sites of digestion in the digestive tract provides promising results, but it is limited due to the high variability that is likely caused by sampling limitations and variation between animals.