Access to grazing reduces enteric methane emission of high-producing dairy cows

Methane emission from cattle significantly contribute to agricultural greenhouse gases. This study evaluated the impact of autumn grazing on enteric methane emission of dairy cows. Twenty-seven cows were subjected to a two-period incomplete Latin square design with three dietary treatments: full indoor feeding (A), grazing (6h) on perennial ryegrass + indoor feeding (B), and grazing (6h) on a multispecies sward of perennial ryegrass, white clover and ribwort plantain + indoor feeding (C). Methane and CO2 emission was measured via GreenFeeds. According to the VEM-method, treatment B and C had a comparable fresh grass dry matter intake, respectively 3.42 kg d-1 and 4.18 kg d-1. Fat and protein corrected milk (FPCM) yield was not significantly affected but was numerically higher for B and C (36.9 kg d-1) than for A (35.8 kg d-1) (P = 0.273). Treatment B and C showed lower methane production, methane intensity and methane yield compared to treatment A (P < 0.001). These results suggest that integrating grazing on conventional and multispecies pastures can reduce methane emission, without compromising productivity. This management innovation aligns with climate change mitigation goals and highlights the potential of diversified grazing strategies to enhance the resilience and sustainability of dairy farms.