Datafile: Effects of multispecies and monoculture forages on nutrient digestibility and fermentation responses using an in vitro rumen simulation technique (RUSITEC)

Abstract

Enteric methane (CH4) emissions are a major contributor to global greenhouse gas emissions. A number of different CH4 mitigation strategies have been proposed, and the inclusion of alternative forages into grazing systems would be a more practical and feasible option. Multispecies swards (MSS) comprise a mixture of forage species, and can increase grassland productivity, reduce nitrogen fertilizer requirements, and reducing fertilizer-associated nitrous-oxide (N2O) emissions. This study investigated the potential benefit of MSS in reducing ruminal CH4 production. Using an in vitro RUSITEC experiment, we compared the effects of different forages (perennial ryegrass, timothy, red clover, white clover, chicory, ribwort plantain and their equi-proportional mixture) on CH4 and gas production, ruminal fermentation parameters and nutrient digestibility. We also compared these responses to perennial ryegrass produced with higher (300N) nitrogen application rate. The experiment was conducted over 21 d, with the initial 14 d allowed for dietary adaptation. Over the subsequent 7 d, there were significant effects of forage type on CH4 production, ruminal fermentation and digestibility. Ribwort plantain, chicory and white clover showed lower CH4 production; chicory incubation produced 73 and 57% less CH4 (mmol d-1) compared to 300N perennial ryegrass and 150N perennial ryegrass incubation respectively. Chicory had 72% lower CH4 produced per unit of organic matter digested (mmol g-1 OMD) than that of 300N perennial ryegrass. Chicory and 300N perennial ryegrass had greater (P < 0.01) nutrient digestibility (DM, OM, CP, NDF, and ADF) than other forages. Greater ammonia nitrogen (NH3-N) concentration was observed in chicory and both clover species, compared to the other forage species (P < 0.01). In general, the response of the six-species mixture was not significantly different to the average response of the six component monocultures. These results show that different grassland forages, especially chicory and white clover, have the potential to reduce ruminal CH4 emissions and could be a promising anti-methanogenic alternative to chemical CH4 inhibitors and feed additives. More generally, the relatively wide variation in CH4 abatement potential across a small sample of plant species suggests the merit of wider screening to identify grassland species with high CH4 abatement potential in vitro.