Nitrous Oxide Prediction in Manure from Pigs Given Mustard x Grapeseed Oil Cakes as a Replacement for Sunflower Meal

During the last century, the emission of nitrous oxide (N₂O) from the livestock sector increased significantly. N₂O is a greenhouse gas with 298-fold higher global warming potential (GWP) than CO₂. Pigs accounted for about 26% of N₂O emissions. The formation of N₂O occurs through nitrification and denitrification processes in manure. This study aimed to estimate N₂O production in the manure of growing-finishing pigs by using our experimental data in the model. The associative effects of dietary mustard and grapeseed oil cakes (MxG), as an alternative for sunflower meal (SFM), on performance and efficiency traits were also determined. Forty growing-finishing pigs were randomly allocated in two groups (2 replicates per group) fed two diets: C diet (based on SFM, 15 wt) and E diet (based on M and G mixture, 7:8 wt:wt). Our model includes as initial input data: body weight (BW), feed intake, nitrogen intake, dietary dry matter, and fibre intake. Using literature prediction equations, including total nitrogen output (TNO) as the main parameter, we established N₂O production expressed as equivalent CO₂ (E-CO2). A decline with 3% for BW (P=0.44), respectively 9.0% for average daily gain (ADG, P=0.21) in pigs given MxG was recorded. Correlated with growth parameters, efficiency traits (feed intake, feed: gain ratio, N and fibre intake) were decreased as well (P>0.05). Dietary addition of MxG led to a 5% lower level of N₂O production in manure. The reduction of TNO was not significant (<7.14% in the E diet compared to the C diet). In our trial, a relatively low N intake percentage is retained in the pigs body (35.56% in the C group and 35.98% in the E group, P>0.05). Based on these results, we conclude that the inclusion of 15% MxG mixture in pigs diets, although slightly declining growth parameters, is a valuable nutritional solution by their contribution to lowering N₂O and N output in the manure.