The overall aim of this article was to investigate options to reduce the net release of greenhouse gas (GHG) emissions into the atmosphere. Enteric methane is the most single significant source of GHG emissions. Different feed additives in forms of algae were looked at to reduce enteric methane (CH4) emissions and potentially improve growth and productivity of the animals but not effect feed efficiency. Red macroalgae Asparagopsis sp was the main form of algae trialled. This research is based in Australia and heavily influenced by the ongoing climate change crisis.
The methane production pathway was described in detail during this article. The end product of ruminant fermentation which is CH4 allows for the essential disposal of metabolic hydrogen which is produced during microbial metabolism. Feed additives have been identified as the most practical strategies to mitigate CH4. There are factors which influence the productivity of these additives and they include the silage quality, the rate of organic matter fermentation, the types of volatile fatty acids produced and the efficiency of microbial protein biosynthesis.
“This should be part of the overall approach to GHG mitigation in terms of overall system efficiency”
This statement indicated that although enteric fermentation is the main source of GHG emissions it is not the only source. Other contributors to GHG emissions must also be reduced such as chemical fertilisers and crop and soil management to make an effective difference to the crisis.
This study was mainly based around the red macroalgae Asparagopsis sp. This algae was seen as having the most significant affect in reducing CH4. Much research has been done on this macroalgae but there is substantially more to be done. It was outlined that although this particular algae was effective at reducing CH4, it was quite hard to grow. This was because it can be known as an invasive species in many areas and can also be high in metals which can be dangerous to other species. The growing of this product has a high carbon footprint which leaves a gap for more research to be done to try find alternative ways such as a controlled aqua culture system to grow it. The feed dosage of this algae is another area were further research needs to be done to eliminate the chance of it effecting the feed efficiency of the animal or causing any harm. This will have to be a trial bases on different types and breeds of animals as they all have different requirements.
Throughout this article it was stated how feed additives are the most effective way of reducing CH4 from enteric fermentation but other systems need to be put in place for the remaining contributors of greenhouse gas emissions to make it more effective. More study needs to be done to ensure these methods can be sustained for a period of time and that it does not come as an expense of the animals productivity. Carbon credit policies were outlined as a possible payment procedure for this method and would also enhance the volume of participation. Although there has been a significant amount of research carried out in the area, it is an ongoing procedure with much more trials and research to be done.
Notes: Katie Noonan, MSc Agri-food Sustainability & Technology student, K.noonan3@nuigalway.ie
Source: (McCauley, Labeeuw et al. 2020).