Abstract
Little is still known about the environmental impacts of exogenous enzyme supplementation in pig and poultry feeding programs. Thus, this study aimed to assess the potential environmental impacts of producing feeds for pigs and broilers by simulating the effects of β-mannanase Hemicell™ HT supplementation through energy savings during diet formulation. Life-cycle assessment standards were applied to simulate a cradle-to-feed mill gate scope. The functional units used were the production of 1 kg of the enzyme and 1 kg of feed at a feed mill gate located in Concórdia, Santa Catarina, Brazil. Climate change, eutrophication, and acidification were the chosen environmental impact categories. Energy savings through β-mannanase supplementation were assessed by different metabolizable energy (ME) matrices (45 or 90 kcal of ME/kg of feed) during diet formulation in different grain production scenarios (Southern and/or Central-West origin). A total of 28 feeds were formulated based on the nutritional requirements and feeding programs described in the Brazilian Tables for Poultry and Swine. The least-cost formulation method was used based on real price averages practiced in a local industry over 12 months. The production of 1 kg of β-mannanase was associated with the emission of 1,800 g of CO2-eq, 4.53 g of PO4-eq, and 7.89 g of SO2-eq. For pig feeds, β-mannanase supplementation mitigated both climate change and eutrophication impacts up to 8.5 and 1.4% (45 kcal of ME/kg of feed) or up to 16.2 and 2.7% (90 kcal of ME/kg of feed) compared to control diets formulated without the enzyme. For broiler feeds, these impacts were mitigated up to 5.6 and 1.1% (45 kcal of ME/kg of feed), respectively. On the other hand, the effect of using β-mannanase on the acidification impact was not consistent among feeds/species. Overall, β-mannanase supplementation reduced the amount of soybean oil in feed formulas, which is associated with high environmental impacts. Consequently, the potential impacts of climate change and eutrophication associated with producing feeds for pigs and broilers were substantially mitigated. These results suggest that β-mannanase supplementation is an eco-friendly feed strategy to reduce the environmental impacts of pig and poultry feeding programs.
Highlights
Pig and poultry feeding programs require a huge amount of feed resources, with several studies indicating feeding as a major source of environmental impact [1,2,3]
17.41 0.97 3,300 0.27 a Starter I, starter II, growing I, growing II, and finishing feeds were formulated based on animals with 1–7, 8–21, 22–33, 34–42, and 43–46 days of age, respectively, and 0.14, 0.59, 1.65, 2.78, and 3.48 kg of body weight, respectively. b β-mannanase supplementation, 45 kcal of metabolizable energy/kg of feed was the energy matrix attributed to the enzyme during diet formulation of broiler feeds. c Values were estimated considering the Brazilian Tables for Poultry and Swine [22]. d Standardized ileal digestible
SO-SO scenariob Climate change, g carbon dioxide equivalent (CO2-eq) Eutrophication, g phosphate equivalent (PO4-eq) Acidification, g sulfur dioxide equivalent (SO2-eq) CW-SO scenarioc Climate change, g CO2-eq Eutrophication, g PO4-eq Acidification, g SO2-eq CW-CW scenariod Climate change, g CO2-eq Eutrophication, g PO4-eq Acidification, g SO2-eq aPre-starter and starter feeds were formulated based on animals with 33–42 and 49–63 days of age, respectively, with 10.8 and 22.5 kg of body weight on average, respectively. bSO-SO scenario: Soybean and corn produced in Southern Brazil. cCW-SO scenario: Soybean produced in Central-West Brazil and corn produced in Southern Brazil. dCW-CW scenario: Soybean and corn produced in Central-West Brazil
Summary
Pig and poultry feeding programs require a huge amount of feed resources, with several studies indicating feeding as a major source of environmental impact [1,2,3]. Regardless of the exact amount of impact attributed to feeding, practically all studies indicated feeding as the most important environmental impact source These results support the hypothesis that novel feeding strategies could be used as eco-friendly strategies to mitigate the environmental impacts of pig and poultry production. Pigs and poultry lack some enzymes, such as β-mannanase, to completely digest β-mannans commonly present in a great variety of feedstuffs, including soybean, corn DDG, sunflower, copra, and palm kernel meal-based diets. This may reduce growth performance once β-mannans are associated with increased intestinal viscosity and decreased nutrient digestibility, following an inflammatory process initiated in response to the β-mannans presence [7,8,9]. When an energy matrix is attributed to the enzyme during feed formulation, some resources are saved, leading to an increase in energyuse efficiency
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