Abstract
The impact of feeding growing pigs with high wheat millrun diets on the global warming potential (GWP) of pork production was investigated. In study 1, a 2 × 2 factorial arrangement of wheat millrun (0 or 30%) and multi-carbohydrase enzyme (0 or 1 mg kg-1) as main effects was utilized. For each of 16 reps, 6 pigs (60.2±2.2 kg BW) were housed in environmental chambers for 14d. Air samples were collected and analyzed for carbon dioxide (CO2); nitrous oxide (N2O); and methane (CH4). In study 2, data from study 1 and performance data obtained from a previous feeding trial were utilized in a life cycle assessment (LCA) framework that included feed production. The Holos farm model (Agriculture and Agri-Food Canada, Lethbridge. AB) was used to estimate emissions from feed production. In study 1, total manure output from pigs fed 30% wheat millrun diets was 30% greater than pigs on the 0% wheat millrun diets (P < 0.05), however, Feeding diets with 30% millrun did not affect greenhouse gas (GHG) output (CH4, 4.7, 4.9; N2O, 0.45, 0.42; CO2, 1610, 1711; mg s-1 without or with millrun inclusion, respectively; P > 0.78). Enzyme supplementation had no effect on GHG production (CH4, 4.5, 5.1; N2O, 0.46, 0.42; CO2, 1808, 1513; mg s-1 without or with enzymes, respectively; P > 0.51). In study 2, the LCA indicated that the inclusion of 30% wheat millrun in diets for growing pigs resulted in approximately a 25% reduction in GWP when compared to the no wheat millrun diets. Our results demonstrate that 30% wheat millrun did not increase GHG output from the pigs, and thus the inclusion of wheat millrun in diets of growing pigs can reduce the GWP of pork production.
How certain are greenhouse gas reductions from bioenergy? Life cycle assessment and uncertainty analysis of wood pellet-to-electricity supply chains from forest residues