WHILE study after study has shown that asparagopsis seaweed reduces methane from livestock, correlations between the feed additive and productivity are less conclusive.

Raw dried Asparagopsis seaweed before it is refined into a feed supplement.

Recent high-profile studies have shown conflicting results, with a cohort of Wagyu cattle owned by the Australian Agricultural Company last year showing reduced weight gains when using asparagopsis and a cohort of asparagopsis-treated Angus cattle, owned by Stockyard Beef, recently showing increased weight gains.

Whether asparagopsis can increase weight gains is a key question for the development of the product, with plenty of concern about the cost of using it and a potential to offset the cost through productivity.

Cost was even highlighted in a recent Climate Change Authority report, with the organisation saying it had heard figures of up to $2/head/day to use it. However, Beef Central understands this was the cost for the original trials of seaweed asparagopsis, with several asparagopsis suppliers now saying it likely to be significantly less than $1/head/day.

University of New England professor Fran Cowley said many had suspected that the additives could result in more efficient animals.

Fran Cowley UNE

She said researchers had been looking for ways to reduce methane for decades, working on the theory that methane is lost energy and that reducing methane output would result in cattle using that energy for productivity.

The question with the feed additives is whether the animals can capture the methane that is being belched out. A question Prof Cowley said was still outstanding.

“We are not seeing consistent capture of that energy by animals, there are a few trials that have showed little hints of it,” Prof Cowley recently told Beef Central’s Weekly Grill podcast.

“To capture that lost energy is one of the next challenges.”

Commercial feed program delivers increased weight gain

The recent trial at Stockyard’s Kerwee Feedlot went a long way to answering questions about whether cattle can capture that energy for productivity. Taking the feed additives from the research feedlot to a commercial operation, it was conducted with 160 Angus steers on a 200-day feeding program.

It must be said that the Stockyard study was not the first to show increased weight gains by using the feed additives, with a study led by Future Feed chief scientist Rob Kinley in 2020 showing a 22pc increase in average daily gain in Brahman-Angus cross steers fed asparagopsis over 90 days.

According to the Stockyard study, the feed additives reduced methane emissions by 51.7pc and increased live weight gain by an average of 19.7kg. It also produced a similar eating quality to conventional beef, which was the same result as the AA Co study.

Matt George

Prominent feedlot nutritionist Dr Matt George, from Bovine Dynamics, said the results of the study possibly highlighted the skill of commercial feedlots and the impact that can have on the overall outcomes.

“The study was done using a commercial feed manufacture facility that starts large numbers of cattle each week, their bunk callers do it for a living, it is a really tightly managed feed formulation and I think we saw the additional benefits out of that,” he said.

“We had full commercial scale diets with full normal ration preparation. While we had input in the AA Co study, it was still done with a small stock mill using tempered barley – which may have partially contributed to the results.”

Reduced feed intake with AA Co study

The AA Co study was conducted over 275 days on 80 head of Wagyu F1 cattle at the UNE’s Tullimba research feedlot.

The asparagopsis treated group produced an average daily gain of 0.87kg/day, versus 0.96kg/day for the control group that was not fed asparagopsis. A reduction in feed intake was attributed to the reduced weight gain.

Dr George helped design of the rations for the study.

“During the asparagopsis adaptation period, the asparagopsis treatment cattle were eating less than the others and we were never able to get them back,” Dr George said.

“I don’t want to over-interpret that or under-interpret it, but it possibly had a role to play in those results.”

The AA Co study concluded with a recommendation for further research to refine feeding protocols asparagopsis/canola oil feed additives.

More study to be done on feed intake

One hypothesis that is emerging to explain the studies with reduced feed intake, is that the breakdown of methane creates a build-up of hydrogen in the rumen, which impacts the appetite of the animal. The theory applies to both asparagopsis and 3NOP.

A methane molecule (CH4) is one part carbon, four parts hydrogen. The additives are said to break down the molecule, turning the carbon into a “long chain fatty acid” – which Dr George said should be energetically more efficient.

Melissa George

He said there are some hypotheses in the literature that the breakdown of the CH4 molecule releases hydrogen into the rumen and causes a build-up.

Dr George’s wife and business partner Dr Melissa George led the Stockyard study. She said the theory had created an entire new field of study with the feed additives.

“They call it a ‘hydrogen sink’ and they are trying to work out how to capture the hydrogen ions and make sure they don’t have a negative impact,” she said.

“Back when we did out trial, it wasn’t really known and now some of these green feeders are fitted with hydrogen sensors as well.”

Stockyard study gives indication of performance response

While the work is being done with the hydrogen build up, Melissa George said the Stockyard study gave some indication that the reduced methane is being turned into energy.

“What we did see was that the majority of the performance response appeared to have occurred in the first 50 days of the feeding period, which is when the greatest methane mitigation occurred,” she said.

“In terms of dry matter intake, it was never different between the two the whole time. So, we know that is not that they are eating any different, it is just that they are utilising their energy resources more efficiently – which is an important distinction.”

In-terms of methane mitigation when cattle get heavier and start eating less, the pair said there was a chance to look feeding the additives in a higher dose at the stages.

• Both Melissa George and Fran Cowley will be presenting to this week’s Beef Ex conference in Brisbane.