PSV-11 Effects of forage processing methods on rumen fermentation characteristics and greenhouse gas emissions of Italian ryegrass (Lolium multiflorum).

Abstract This study aimed to estimate the effect of processing methods of Italian ryegrass (IRG, Lolium multiflorum) on fermentation characteristics and greenhouse gas emissions in the rumen. The IRG was harvested at the earing stage, cut 3-5 cm in length, and divided into fresh forage, hay, and silage in triplicates. The harvested IRG were freeze-dried, air-dried for 5 days, and ensiled for 90 days for the forage processing methods of fresh forage, hay, and silage, respectively. Rumen fluid was collected from two cannulated Hanwoo cows and mixed with Van soest medium at a 1:2 ratio for rumen buffer. Rumen buffer (30 mL) was incubated with each forage (0.3 g) in quadruplicates at 39oC for 48 h. Silage had higher (p< 0.05) crude protein, ether extract, crude ash, and acid detergent fiber than fresh forage and hay. In contrast, fresh forage had higher (p< 0.05) in vitro dry matter digestibility than hay and silage. In the rumen, silage had a lower (p< 0.05) total VFA, acetate, and A:P ratio than fresh forage but higher (p< 0.05) pH and propionate. Silage had a lower (p< 0.05) total gas emission than the other forage processing methods, while fresh forage and silage had lower (p< 0.05) CO2 and CH4 emissions. Hay and silage had lower (p< 0.05) methanogenic archaea than fresh forage, while fresh forage and silage had lower (p< 0.05) methanobrevibacter smithii than hay. Additionally, fresh forage had lower (p< 0.05) methanomicrobium mobile than silage. Therefore, this study concludes that the ensiling process of IRG recommends greenhouse gas mitigation in the rumen.