Seaweed supplementation to mitigate methane (CH4) emissions by cattle (SeaCH4NGE)

The results of SeaCH4NGE include a detailed analysis of the chemical composition of seaweeds, including heavy metals and nutritional composition. This elucidated that iodine was the main concern prior to feeding trials. Chemical analysis of the compounds that may be responsible for methane reduction showed that for the seaweeds investigated the reduction seen in-vitro was likely due to compounds called phlorotannins rather than bromoform. The in-vitro screening of the seaweeds showed a some reduction of methane, but the reduction was seaweed species dependent. The reduction was dose dependent, i.e. higher amount of seaweed inclusion resulted in larger methane reduction in-vitro. The same two seaweed species were used for a Rusitec experiment (in-vitro) which is a very comprehensive analysis which provides additional information. The in-vivo trial carried out showed that feeding A. nodosum and Fucus vesiculosus to cattle has a relatively small effect on methane emission or yield. However, phlorotannins are known to have other beneficial effects when consumed by ruminants. The report further contains responses from a questionnaire to UK cattle farmers regarding their stance on seaweed supplementation and environmental matters. This report is closed until 31.12.2023. ____ Niðurstöður SeaCH4NGE fela í sér ítarlega greiningu á efnasamsetningu þangs, þ.m.t þungmálma og næringarsamsetningu. Joð styrkur reyndist helsti takmarkandi þáttur varðandi þang sem fóðurbæti. Líklegt er að sú metan minnkun sem sást með tilraunum á metanframleiðslu á rannsóknarstofu (in vitro) væri vegna efnasambanda sem kallast flórótannín frekar en brómóforms sem er þekkt efni sem getur minnkað metanframleiðslu jórturdýra. In vitro skimun þangsins sýndi hóflega minnkun metans, en lægri metanframleiðsla var háð þangtegundum. Lækkunin var skammtaháð, þ.e.a.s. með því að nota meira magn af þangi mátti sjá meiri metan minnkun in vitro. Sömu tvær þangtegundirnar voru notaðar við Rusitec tilraun (in vitro) sem er mjög yfirgripsmikil greining sem veitir frekari upplýsingar. In-vivo rannsókn á kúm sýndi að fóðrun nautgripa með A. nodosum og Fucus vesiculosus hefur tiltölulega lítil áhrif á losun metans. Hins vegar er vitað að flórótannín hafa önnur jákvæð áhrif þegar þau eru neytt af jórturdýrum. Skýrslan inniheldur einnig könnun sem var gerð á viðhorfi breskra kúabænda til þörungagjafar og loftslagsmála. Þessari skýrsla er lokað til 31.12.2023.Funding: EIT Foo