PSX-21 Supplementing essential oil blend and fumaric acid in calf feed influenced rumen fermentation and greenhouse gases emission

Abstract

Abstract Essential oils (EO) and fumaric acid (FA) are known for their ability to reduce greenhouse gas (GHG) emissions in ruminant animals. This study aimed to investigate the combined impact of essential oil blend (EOB) and FA (EF) on in vitro fermentation, total gas and volatile fatty acid (VFA) production and GHG emissions of a calf feed in a 24 h batch culture study. Rumen-cannulated black Angus beef cows (n = 3) served as inoculum donors. The calf feed contained 910, 5.8, 70.9, 792, 111, 72 g/kg dry matter (DM), fat, ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL), respectively. The EOB contained equal proportions of ginger, anise, peppermint, oregano and thyme. FA was added at 3% along with EOB at 10, 20, 30 and 40 µL/g calf feed. Five treatments evaluated were Control (without additives), EF10, EF20, EF30, and EF40. Results showed that pH and digestibility of DM, NDF, ADF were not significantly (P > 0.05) affected by the EF treatments (Table 1). ADL digestibility decreased linearly (P < 0.001) with increasing EF dosage. EF40 increased (P < 0.05) cellulose digestibility by approximately 11% compared with EF10. Total gas, methane and carbon dioxide production decreased (linear, quadratic, P < 0.001) with EF inclusion (Table 2). Ammonia concentration decreased linearly (P = 0.009) with increasing EF dosage, while hydrogen sulfide gas was not affected. EF inclusion reduced (P < 0.001) total VFA, acetate but increased propionate and butyrate proportion (Table 3). In conclusion, the combination of EOB and FA effectively mitigated GHG emissions without compromising nutrient digestibility in calves. Therefore, incorporating EOB at 10 µL/g and FA at 3% in calf feed is recommended as an effective nutritional strategy to reduce GHG emissions in calves.