Guest essay by Eric Worrall

Greens are celebrating that feeding algae to cows which breaks down into the organo-halide Bromoform seems to drastically reduce their flatulence of powerful greenhouse gasses. But the toxicology description of Bromoform suggests the need for a lot more caution before implementing this measure on a large scale.

Clearing the air: who should do the most to tackle climate change? By Nicole Hasham

4 August 2018 — 11:37pm In the balmy waters off Queensland’s coast grows a red algae that promises to help rescue the planet. Sprinkled into the feed of cows, trials show the super-seaweed can all but eliminate greenhouse gas emissions produced by their burps and flatulence. But the algae – Asparagopsis taxiformis – has never been farmed at scale. Scuba divers must painstakingly pluck it from the ocean. As research founder Rob Kinley of the CSIRO says, the challenges of commercial production are immense. “The potential is global … but the barrier is the supply of seaweed. The scale of that is monstrous,” Kinley said. “Every country wants to improve their environmental footprint from agriculture … what we need to do is come up with a massive supply.” …

Read more: https://www.smh.com.au/politics/federal/clearing-the-air-who-should-do-the-most-to-tackle-climate-change-20180803-p4zvfn.html

Tracking down the study;

The red macroalgae Asparagopsis taxiformis is a potent naturalantimethanogenic that reduces methane production duringin vitro fermentation with rumen ﬂuid Robert D. Kinley, Rocky de Nys, Matthew J. Vucko, Lorenna Machado and Nigel W. Tomkins CSIRO Agriculture, Australian Tropical Science and Innovation Precinct, James Cook University,Townsville, Qld 4811, Australia. BMACRO-Centre for Macroalgal Resources and Biotechnology, College of Marine and Environmental Sciences,James Cook University, Townsville, Qld 4811, Australia.CCorresponding author. Email: rob.kinley@csiro.auAbstract. Livestock feed modiﬁcation is a viable method for reducing methane emissions from ruminant livestock. Ruminant enteric methane is responsible approximately to 10% of greenhouse gas emissions in Australia. Some species of macroalgae have antimethanogenic activity on in vitro fermentation. This study used in vitro fermentation with rumeninoculum to characterise increasing inclusion rates of the red macroalga Asparagopsis taxiformis on enteric methaneproduction and digestive efﬁciency throughout 72-h fermentations. At dose levels at 1% of substrate organic matter there wasminimal effect on gas and methane production. However, inclusion at 2% reduced gas and eliminated methane production inthe fermentations indicating a minimum inhibitory dose level. There was no negative impact on substrate digestibility for macroalgae inclusion at 5%, however, a signiﬁcant reduction was observed with 10% inclusion. Total volatile fatty acids were not signiﬁcantly affected with 2% inclusion and the acetate levels were reduced in favour of increased propionate and, to alesser extent, butyrate which increased linearly with increasing dose levels. A barrier to commercialisation of Asparagopsis isthe mass production of this speciﬁc macroalgal biomass at a scale to provide supplementation to livestock. Another area requiring characterisation is the most appropriate method for processing (dehydration) and feeding to livestock in systems with variable feed quality and content. The in vitro assessment method used here clearly demonstrated that Asparagopsis caninhibit methanogenesis at very low inclusion levels whereas the effect in vivo has yet to be confirmed.

Read more: https://www.researchgate.net/publication/293800275_The_red_macroalgae_Asparagopsis_taxiformis_is_a_potent_natural_antimethanogenic_that_reduces_methane_production_during_in_vitro_fermentation_with_rumen_fluid

From the full study;

… It is known that the antibacterial defence mechanism of Asparagopsis is predominantly a result of the secondary metabolite bromoform (CHBr3) naturally present in themacroalgal biomass (Paul et al.2006). Bromoform is similar chemically and in antimethanogenic potency to that of bromochloromethane (BCM; CH2BrCl). In previous in vivo experiments investigating enteric CH4 abatement, BCM induced abatement in Brahman steers of 93% and 50% after separate 28 and 90 days feeding regimes, respectively (Tomkinset al.2009). However, BCM has been banned from manufacture and use in Australia due to its contribution to ozone depletion. The mode of action of BCM was described previously asinhibition of the methanogenic pathway at the ﬁnal step by inhibition of the cobamide-dependent methyl transferase stepin release of CH4(Denman et al.2007). In that study inhibition of methanogenesis occurred immediately however the methanogen populations were only found to be reduced after several hours,thus the observed lag in the population decline suggested that the inhibition of methanogenesis directly affected growth of methanogens. They also commented that BCM would be removed from the rumen due to ruminal ﬂow and unless it was replaced CH4 inhibition would decline …

Read more: Same link as above

The following from the toxicology description of Bromoform on Wikipedia caught my eye.

… The substance may be hazardous to the environment, and special attention should be given to aquatic organisms. Its volatility and environmental persistence makes bromoform’s release, either as liquid or vapor, strongly inadvisable. Bromoform can be absorbed into the body by inhalation and through the skin. The substance is irritating to the respiratory tract, the eyes, and the skin, and may cause effects on the central nervous system and liver, resulting in impaired functions. It is soluble in about 800 parts water and is miscible with alcohol, benzene, chloroform, ether, petroleum ether, acetone, and oils. Its LD50 is 7.2 mmol/kg in mice, or 1.8g/kg. Bromoform is a confirmed animal carcinogen; (ACGIH 2004). Carcinogen category: 3B; (DFG 2004). …

Read more: https://en.wikipedia.org/wiki/Bromoform

The study authors celebrate that Bromoform is not the closely related chemical BCM, which has been banned in Australia because of its ozone depleting potential. But Bromohalides, especially comparatively lightweight halides like Bromoform, are also a potential ozone risk. Having said that, there is substantial natural production of Bromohalides from the ocean, possibly from relatives of the algae which greens want to feed to cows.

It is possible all the Bromoform is broken down in the cow’s stomachs, that this known animal carcinogen doesn’t contaminate the beef in sufficient quantities to present a hazard to humans or to the cows themselves, that this persistent environmental toxin won’t end up poisoning the farmer’s fields, that we can overlook the ozone depleting potential of thousands of acres of fields slowly evaporating eliminated Bromoform into the atmosphere.

But all these potential issues should be carefully reviewed, before rushing this “solution” to reducing agricultural methane into mainstream production.

We all expect climate obsessed governments to be sensible about this, right?

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