Seaweeds – Cows – Methane: Introducing seaweeds in dairy cattle diets and their effects on enteric methane production, ruminal microbiome, food safety and animal health

Cows naturally emit greenhouse gasses, specifically methane. Greenhouse gasses are important to capture warmth on earth, but having too many greenhouse gasses in the atmosphere results in increasing temperature. This is described as the enhanced greenhouse gas effect. Reducing the amount of methane produced by cows can limit this increase in temperature. This thesis investigates if feeding seaweeds to cows can reduce the methane production. Depending on seaweed species, and specifically the contents, some can reduce methane, but without further processing most species have a limited effect. Specifically the seaweeds called “Asparagopsis” effectively reduce methane, due to the high concentrations of bromoform. However, feeding Asparagopsis can also reduce the feed intake or result in bromoform residues in milk and urine. Per seaweed species there are specific challenges in its use. These challenges are further explored and discussed in the thesis, and places reducing methane production in perspective with animal health and food safety.