July 02, 2018

Seaweed resurfaces

A six-month trial of continuous feeding is the next step in a project that has confirmed seaweed can prevent methane emissions from dairy cows.

Preliminary results at the University of California Davis show an extraordinary 99% reduction in methane emissions in the world’s first trial of feeding seaweed to live dairy cows. Professor Emeritus Ermias Kebreab told Fonterra the next stage of his programme is to establish any long-term impacts of using seaweed, including what effect, if any, it has on the taste and composition of the milk produced by cows.

“The results are not final but so far we are seeing substantial emission reductions,” Professor Kebreab says.

Kebreab and his team have been mixing a small amount of red seaweed - about 1% - into the regular feed of a dozen Holstein cows for about a year. Four times a day, the cows are taken to a device that measures the amount of methane in their breath as they eat. To make the seaweed more palatable, it has been mixed with molasses.

Scientists have looked at seaweed several times as a possible solution to reducing the methane expelled by cows. Most were lab based tests although in Australia scientists did trial red seaweed with sheep, using a high-fibre pelleted diet over 72days. It showed methane emissions were reduced by 50-80% however some sheep showed some adverse health impacts. The researchers concluded further investigation into animal health and palatability issues is needed.

New Zealand scientists acknowledge the methane negating impact that seaweed seems to have but have concerns over the active ingredient in it that could reduce the potential for widespread use.

Bromoform is part of the chemical make-up of red seaweed. This chemical is known to be an ozone-depleting substance, so increased production of it is likely to be contentious. The problem isn’t so much the cows emitting bromoform, it is the emission of the compound while the seaweed grows. This would prevent – or at least provide big hurdles – for red seaweed to be farmed on a commercial basis. Specific to New Zealand, red seaweed is a tropical seaweed and it’s unsure how it would grow in our waters, while the energy cost and emissions from drying and transporting it in large volumes would have to be accurately assessed against the benefits of reduced methane emissions.

One possible alternative is to manufacture the active ingredient(s) for direct addition into ruminant feeds, possibly as a slow release. However the issues of ozone depletion, palatability, animal health and milk composition would need to be addressed to meet our animal welfare codes and milk safety and quality standards. Suffice to say, there is more research to be done before we can consider using red seaweed to solve our methane issues. We’ll be keeping an eye on developments.

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