Adding 1.0% and 2.0% North Atlantic brown seaweed to pregnant replacement heifers cut methane emissions by about 8.2% and 8.7% without affecting growth performance
Using 20 eighteen-month-old pregnant crossbred replacement heifers averaging 383 kg, this study fed 0.0%, 0.5%, 1.0%, and 2.0% North Atlantic brown seaweed (Atlantic GRO®, made of Laminaria longicruris and Fucus vesiculosus) on a dry matter basis over a 50-day performance trial, then measured gas emissions in 16 of them with headbox metabolic chambers for two 24-h periods; no supplementation level adversely affected growth performance (p > 0.51), while the 1.0% and 2.0% groups emitted about 8.2% and 8.7% less methane than controls (p < 0.05), with significantly lower carbon dioxide emissions and oxygen consumption as well (p < 0.05).