P.PSH.1353 - Effect of Asparagopsis extract in a canola oil carrier for long-fed Wagyu cattle

Summary

This project aimed to understand the methane mitigation achievable in long-fed Wagyu production systems, and the implications for cattle feedlot performance, and carcase grading, residues and trained sensory panel evaluation, in the longest feeding trial of an Asparagopsis product reported to-date (275 days).

Objectives

The objectives of this project were to determine the effect of an Asparagopsis extract in a canola oil carrier on:
• Enteric methane production of long-fed wagyu feedlot cattle (using C-Lock Greenfeed units as the emissions monitoring technique)
• Animal health and performance metrics
• Carcase grading characteristics
• Concentrations of bromoform, iodide and bromide in carcase, fat, liver and kidney depots
• Trained sensory panel evaluation including tenderness and flavour standards designed for AACo’s Westholme product.

Key findings

Feeding Asparagopsis oil at 25 mg/kg DM reduced methane production by 28 % from the Control diet over the whole feeding period, along with a 22% decrease in methane yield (g/kg DMI). Asparagopsis oil reduced feed intake consistently (by 7.93 % overall) without improvement in feed efficiency. This resulted in persistently reduced liveweight gain (by 9.38 % overall), and a trend to reduce carcase weight by 15.1 kg. Due to the decline in liveweight, methane intensity (g/kg LW gain) did not differ between treatments. Other carcase grading traits were not affected by Asparagopsis oil supplementation, and there was no effect on trained sensory panel attributes. Consistent with other research, there was no bromoform detectible in meat or offal. Canola oil stabilised bromoform over the duration of use in this study with no volatilisation evident in vegetable oil tanks at the feedlot.

Benefits to industry

The research project has been one of the first commercialisation trials of Asparagopsis products conducted under Australian feedlot industry-relevant conditions, and is the largest-scale, and longest feeding experiments conducted to-date on Asparagopsis products. As such, it provides essential data to support the business case for adoption of Asparagopsis oil into long-fed feedlot programs, in terms of cattle productivity, and methane abatement. It has highlighted that further research is required to understand the reasons for feed intake depression caused by Asparagopsis oil, and management strategies which could overcome this, so that Asparagopsis oil can be widely adopted with confidence.

MLA action

MLA is committed to researching a range of strategies to reducing enteric methane in beef cattle. This is not limited to asparagopsis, but includes other molecules and strategies. This trial was an important piece in the innovation pathway for these products, and has highlighted areas for future R&D for commercializers to focus on.

It is important to note, this is a single experiment, from a single market category of feedlot cattle and further research independent of MLA is planned to be delivered by the Federal Government MERIL grants program during 2023/2024, determining the responses of Asparagopsis in other feedlot diets.

Results of two Meat Standards Australia (untrained sensory panel data) projects on asparagopsis will be published in 2024.

Future research

Further research is required to refine feeding protocols for Asparagopsis oil supplements to overcome intake depression in Wagyu cattle. This may not be unique to Asparagopsis, and should consider not only dose titration and adaptation protocols, but potentially, co-feeding of hydrogen sinks or products that promote hydrogen utilisation in the rumen together with methane inhibitors. Results of Meat Standards Australia (untrained sensory panel data) will be available in May, 2024 via MLA Project L.EQT.2306.