Mirka Thorsteinsson1,2,3, Martin Riis Weisbjerg1,2,3, Peter Lund1,2,3, Annette Bruhn3,4, Anne Louise Frydendahl Hellwing1, and Mette Olaf Nielsen1,2,3
1Department of Animal Science, Aarhus University, Blichers Alle 20, Foulum, 8830 Tjele, Denmark
2iCLIMATE – Interdisciplinary Centre for Climate Change, Aarhus University, Denmark
3CBIO – Centre for Circular Bioeconomy, Aarhus University, Denmark
4Department of Ecoscience – Marine Ecology, C.F. Møllers Alle 4-6, 8000 Aarhus, Denmark
Methane is formed as a by-product during fermentation of feed primarily in the forestomachs of ruminants. However, methane is a potent greenhouse gas, and thus of concern in relation to climate change. Seaweeds procured from the Northern hemisphere have shown potential to reduce in vitro methane production. This study aimed to investigate the in vivo effects of three brown seaweeds (Phaeophyceae) on enteric methane emission and feed intake of dairy cows. The experiment was conducted as a 4 × 4 Latin square design using four lactating rumen, duodenal, and ileal cannulated Danish Holstein dairy cows. Seaweed products were dried and ground prior to mixing into the experimental rations. The cows were fed a ration without any seaweed or the same ration diluted with, on a dry matter-basis, either 4% ensiled Saccharina latissima, 4% Ascophyllum nodosum, or 2% Sargassum muticum, for periods of 21 days. Methane emission was measured during the last 4 days of each period using respiration chambers. Additionally, dry matter intake (DMI) and milk yield were recorded. Milk yield and DMI were unaffected by the dietary inclusion of seaweeds (P-value 0.51 and 0.34, respectively). Moreover, none of the three seaweeds, added to rations, affected methane emission expressed as g/d or as g/kg DMI (P-value 0.14 and 0.84, respectively). In conclusion, the inclusion of dried and ground A. nodosum, S. muticum, or ensiled S. latissima in the feed ration of dairy cows had no impact on neither cow productivity nor methane emission.