text: Mitigating methane emissions from livestock production is essential in fighting climate change. The seaweed from the genus Asparagopsis has been identified as a highly effective supplement, capable of reducing methane emissions in livestock by 80% or more. Although progress has been made to investigate the effect of seaweed supplementation in feedlots, there have been no demonstrations of seaweed supplementation in commercial production settings. This approach is significant because methane emissions are higher when animals consume lower-quality feed, which is more common in grazing systems.
  The objective of this project is to showcase the use of low-dose seaweed supplementation to decrease methane emissions in pregnant cows grazing on low-quality feed. Forty-two pregnant black Angus cows were allocated to either a control or a seaweed group. Cows were supplemented with an average duration of 43 days prior to calving. The gas emissions from cows and the live weight of the progeny were measured using two different devices (GreenFeed vs. Bosean K-600). This project represents a significant advancement in providing valuable and practical solutions for cattle producers to reduce emissions while grazing pasture and the potential use of a low-cost device to monitor the greenhouse gas emissions in livestock.
  To meet the global target of limiting temperature increase to 1.5°C, agricultural methane emissions need to be cut significantly. In Australia, livestock farming alone accounts for about 70% of these
  emissions (1). Mitigating these emissions is essential in fighting climate change.
  In recent years, seaweed (specifically Asparagopsis taxiformis and Asparagopsis armata) has gained industry interest as a feed supplement for cattle due to its level of bromoform and other halogenated metabolites (2), which can reduce methanogenesis by up to 98% (3).
  Farmers, their advisers and industry need clear information on dosage, approach to supplementation, and feed management to ensure the health and wellbeing of their cattle, while reducing their emissions.
  The University of Adelaide and partners investigated the dosage and best practice approach of seaweed supplementation. They prioritised supplementing pregnant cows on poor-quality feed – typical of low-rainfall grazing systems – to reduce methane emissions, which tend to be higher with lower feed quality.
  - Panchasara H, Samrat NH & Islam N. 2021. Greenhouse gas emissions trends and mitigation measures in Australian agriculture sector – A review. Agriculture 11:85.
  - Muizelaar W et al. 2023. Evaluation of 3 northwest European seaweed species on enteric methane production and lactational performance of Holstein-Friesian dairy cows. Journal of Dairy Science 106:4622-4633.
  - Glasson CRK et al. 2022. Benefits and risks of including the bromoform containing seaweed Asparagopsis in feed for the reduction of methane production from ruminants. Algal Research 64:102673.
  Key achievements and results:
  The research improved understanding of the efficacy of using a low-dose bromoform bioactive feed supplement in reducing methane emissions in pregnant cows grazing on low-quality feed, providing valuable insights on dosage and approach, emissions, and animal health and wellbeing.
  The findings will be used to make recommendations for the livestock industry nationally and internationally. Specific results on dosage rates, emissions, and cow health and performance will be shared following upcoming publication in a peer-reviewed scientific journal.
  New approach to measuring methane on-farm
  The research produced exciting insights into the effectiveness of using hand-held units to measure gas emissions of black Angus cows.
  The team validated that the low-cost, hand-held ‘BoseanK-600’ device is a reliable tool for monitoring emissions on-farm and in the livestock industry. While more data needs to be collected, this represents a significant advance to the computer models producers have previously relied upon to predict methane emissions.
  More research will further validate the potential of this approach for adoption by the livestock industry as an on-farm tool to measure methane emissions, and to improve the overall sustainability of the sector.
  Project case study
  For further information and the technical report for this project, contact Project Lead Dr Mariana Caetano, University of Adelaide, at firstname.lastname@example.org.