Methane emissions and rumen metabolite concentrations in cattle fed two different silages

Abstract

In this study, 18 animals were fed two forage-based diets: red clover (RC) and grass silage (GS), in a crossover-design experiment in which methane (CH4) emissions were recorded in respiration chambers. Rumen samples obtained through naso-gastric sampling tubes were analysed by NMR. Methane yield (g/kg DM) was significantly lower from animals fed RC (17.8 ± 3.17) compared to GS (21.2 ± 4.61) p = 0.008. In total 42 metabolites were identified, 6 showing significant differences between diets (acetate, propionate, butyrate, valerate, 3-phenylopropionate, and 2-hydroxyvalerate). Partial least squares discriminant analysis (PLS-DA) was used to assess which metabolites were more important to distinguish between diets and partial least squares (PLS) regressions were used to assess which metabolites were more strongly associated with the variation in CH4 emissions. Acetate, butyrate and propionate along with dimethylamine were important for the distinction between diets according to the PLS-DA results. PLS regression revealed that diet and dry matter intake are key factors to explain CH4 variation when included in the model. Additionally, PLS was conducted within diet, revealing that the association between metabolites and CH4 emissions can be conditioned by diet. These results provide new insights into the methylotrophic methanogenic pathway, confirming that metabolite profiles change according to diet composition, with consequences for CH4 emissions.

Performance and enteric methane emissions from housed beef cattle fed silage produced on pastures with different forage profiles

“…Dewhurst et al (2003), however, observed no significant differences in milk yield for cows offered ryegrass silage, or silage from ryegrass with white or red clover (Trifolium pratense) (50:50). Bica et al (2022) compared rumen metabolite concentration and CH 4 emissions from beef cattle offered red clover silage or ryegrass silage, but not a mixed sward observed no significant differences for CH 4 emissions. Wang et al (2020) conducted an in vitro experiment comparing different ryegrass cultivars and concluded that AberMagic resulted in a slightly lower CH 4 yield.…”

Effect of grassland cutting frequency, species mixture, wilting and fermentation pattern of grass silages on in vitro methane yield

“…A previous study showed that a greater NDFom concentration resulted in lower CH 4 production 13 , which might explain why CH 4 production was lower in T than RG in the present experiment. It has been shown that diets with red clover reduced in vivo CH 4 production compared to diets with grass in cattle (17.8 vs 21.2 g/kg DM intake, respectively) 52 . However, in the present study, we did not observe lower CH 4 production in T + RC compared to T. This supports earlier findings showing no such effect in diets with 60/40 perennial ryegrass and clover 20 .…”