Seaweed-based feed ingredients are among future solutions being highlighted to help farmers reduce methane emissions in cattle and their share of climate change.
Prof Woodford said it was hoped that bromoform in the seaweed would reduce methane production, but promoters of technical ruminant solutions were overlooking nutritional issues that made this unlikely.
‘‘Yes they will kill off the methanogens alright, but they will also flow into the milk. .... Some people don’t like that story because it spoils their story and their investment opportunity, but now that it’s there, gosh it’s pretty serious.’’
Prof Woodford said it could flow into meat, but this had yet to be confirmed.
‘‘Bromoform are toxic to humans as well as toxic to methanogens, so milk containing bromoforms is not going to sell very well. Even if bromoforms do not accumulate in meat there are huge practicalities involved in commercialising bromoforms.’’
He doubts enough seaweed farms could be built to do this.
‘‘So there’s lots of hype around feeding seaweed containing bromoforms to kill off the methanogens.’’
The former Professor of Farm Management and Agribusiness was among speakers at a New Zealand Institute of Agricultural & Horticultural Science forum at Lincoln University on how farmers can mitigate climate change.
Prof Woodford said earlier talks by Climate Change Minister James Shaw and Climate Change Commission chairman Dr Rod Carr had put a lot of reliance on ‘‘magic bullets’’ to lower emissions.
‘‘Well we’re not — there are no magic bullets in regard to methane from pastoral ruminant digestion.’’
Prof Woodford said methanogens were fundamental to ruminant nutrition and played a major role for ruminant cows to turn cellulose into metabolisable energy.
This is excreted by burping and there is no simple alternative way of dealing with the large amount of hydrogen that comes from cellulose fermentation.
He said scientific barriers also existed around anti-methanogenic 3-NOP being effective outside of feedlots, and farmers should not hold their breath on this being transferred into pastoral agriculture.
Early hype around vaccines had yet to materialise in the commercial world. However, breeding for low methane emissions was possible and worked best with high quality feed, so it would be interesting to see how this translated to hard backcountry, he said.
He said pastoral agriculture was fundamental to the New Zealand economy and needed to remain vibrant, while methane was also fundamental to livestock digestion.
Methane had been reduced per kilogram of sheepmeat by about 30% over the past 30 years with more productive animals and dairy had reduced methane per kilogram of milksolids by about 20%.
‘‘It’s a wonderful story but you hardly hear it and the urban community surely does not know that story. ... It’s not getting out there to the masses. Each efficiency gain becomes more challenging from here in. It’s going to be hard graft and it won’t be spectacular.’’
There could be modest savings from removing emissions from effluent — perhaps 4% of NZ’s total methane emissions.
Prof Woodford said he agreed with Mr Shaw and Dr Carr that New Zealand had to stop thinking of forestry as the offsetting tool for fossil fuel emissions.
‘‘Instead we need to reconfigure our thinking and look at land-based emissions versus fossil fuel emissions. That takes quite a change in thinking, but if we look at the total land-based sector it’s possible for NZ to have net zero from the land-based industries compromising agriculture and forestry and all the conservation land as well.’’
He said part of that was to put some of the remote and steep land-class country prone to erosion into permanent forestry of exotic trees and potentially transitioning into native trees.
