PSXI-24 Comparative analysis of the chemical composition and methane production from different total mixed fermentation (TMF) diets fed to Hanwoo cattle

Abstract Total mixed fermentation (TMF) feed is a mixture of forage, concentrate, and useful microorganisms utilized to enhance nutrient availability and livestock well-being. Recognized for its potential benefits, TMF has been noted to decrease acetate production while increasing propionate production in the rumen. However, a comprehensive understanding of its composition and potential impact on methane production remains lacking. Thus, this study investigated the chemical composition and in vitro methane production associated with different TMF diets designed for different Hanwoo cattle groups. A comparative analysis of 26 TMF diets, including 3 designed for calves, 7 for growing, 6 for early fattening, 6 for late fattening, and 4 for breeding, was conducted to examine their chemical composition. The TMF samples were submitted to Cumberland Valley Analysis Service (CVAS) for chemical analysis. Principal component analysis (PCA) was employed to visualize the TMF according to the Hanwoo feed-type groups and the chemical compositions to estimate the optimal parameters among different TMFs. An in vitro gas production trial was conducted to determine the effects of different TMFs on methane production. Gas samples were collected at 12 and 24 h of incubation and methane (CH4) concentration was measured using a gas chromatograph. All data were analyzed using the SAS 9.4, with P 0.05 being considered significant. Analysis of the chemical composition of different TMFs, including crude protein, neutral detergent fiber, acid detergent fiber, ethanol-soluble CHO, and total digestible nutrients, showed no significant differences (P 0.05) between the TMFs according to each Hanwoo category (calf, growing, early fattening, late fattening, and breeding). PCA revealed that digestibility-related parameters and fatty acid content were the main factors discriminating among the TMFs, with the TMFs for calves having the least fat content and those for the late fattening period having the greatest digestibility. Moreover, optimal TMFs were identified for each category of Hanwoo based on their chemical compositions. Among the TMFs tailored for each category of Hanwoo, TMF16, TMF23, TMF24, TMF25, and TMF26 were shown to have an optimal chemical composition for calves, growing, early fattening, late fattening, and breeding, respectively. A minimal reduction in CH4 production at 24 h incubation was observed in specific TMFs across different Hanwoo categories. Notably, TMF14 (7.21%) and TMF22 (8.52%) for calves, TMF05 (4.74%) for early fattening, TMF01 (3.76%) and TMF11 (3.76%) for late fattening exhibited reduced CH4 production. Additionally, CH4 production at 24 h incubation was significantly reduced (P 0.05) by 23.06% and 10.90% in TMF15 and TMF26, respectively, both categorized for breeding TMF. Overall, while the chemical compositions of various TMFs did not significantly differ, TMF showed the potential to mitigate methane production in Hanwoo cattle.