Feeding asparagopsis armata to cattle reduces methane by up to 99% when fed at 2% of total feed (by dry matter) and by up to 80% when fed at 0.6% of dry matter. It’s invasive in the UK, partly due to it being farmed in the Irish Sea to make wrinkle cream. As part of our Culm Restoration project, we’re going to get a house cow, so we want some asparagopsis to feed to the cow. We can collect it from the beach, but we’re also going to try to grow some.
This is a work in progress and the methodology of the experiment may well change as we proceed. If you have any information that you feel would be useful, please do contact us to let us know.
Asparagopsis Armata is a red macroalgae which reduces methane by 99% when fed to cattle at 2% and by 80% when fed at 0.6% of their feed as dry matter(DM).
Asparagopsis armata grows fastest at temperatures between 15°c and 24°c. It is damaged by temperatures of over 29°c.
There are 2 stages to Asparagopsis in British waters. The 2 stages were previously thought to be different species, so the stage that exists in winter has its own name: Falkenbergia rufolanosa. During this stage it is a small fluffy looking macroalgae. It is during the summer, that it grows the majority of its mass. The change between stages of growth are based on day length.
We are assuming (partly for ease of calculations) that our cow with a calf will require 10kg of DM per day. We therefore require between 21.9kg (@0.6% DM) and 73kg (@2% DM) of seaweed by dry matter per year. It’s hard to find figures for tank grown seaweed production per M³, but anecdotal evidence shows that 140kg (fresh weight) per m3 is possible. Water content of asparagopsis armata is around 70%. This therefore equates to 42kg DM. In practice, if we could get half of this yield so required 2M³ to grow 42kg, we’d be quite happy.
We experimented with growing asparagopsis armata before covid 19 became a thing. We killed the seaweed, due (we think) to excessive temperature fluctuation. We have not been able to get to the coast to collect more samples and also, we have had a change of priorities, due to covid and its consequences. When we do resume the experiment, we are going to try growing it under artificial light in an insulated container. This is a method that people use to commercially grow seaweed in America, so we know that it’s feasible.