Vials of goat rumen fluid reacting with the feed combinations.

A COMBINATION of emu apple and oats has proven the winner in an Australian-first comparison trial into greenhouse gas-restricting feed for goats.

The sub-tropical browse emu apple (Owenia acidula) combined with green fresh-cut oats had the most desirable fermentation pattern and lowest methane emissions than other alternatives, according to laboratory analyses led by the University of Queensland.

The wooden-spooner was Mitchell grass, which had the second-highest methane concentration and, because of its poor digestibility, the greatest methane yield.

The researchers were looking for the best balance of feed to improve digestibility and reduce methane emissions from goats in Australia’s tropical arid and semi-arid regions.

Associate Professor Sarah Meale

Using goat rumen samples to measure plant fermentation responses, they compared 17 Queensland browses and eight forage species, including coolabahs, wilgas and beefwood, along with forages such as Rhodes grass and buffel.

The research team found that oats were the most digestible feed and offered the lowest methane production. With a 75:25 blend with emu apple, total digestibility reached 62.75 percent in the laboratory while methane yield amounted to 10.11 mL/g digested DM.

This next-best combination was a 50pc forage oats and 50pc emu apple blend, with a digestibility of 60.72pc and methane yield of 11.08 mL/g digested DM.

Research lead, Associate Professor Sarah Meale, said goat production is rapidly expanding in tropical arid and semi-arid regions, yet limited knowledge exists on the feed they consume.

She said that, while methane from goat farming accounts for 4pc of global enteric methane emissions, goat populations have expanded faster than any other ruminant species since 2000, increasing by 39pc and surpassing 1.2 billion head globally in 2023.

“Crucially, the impact of this growth on methane emissions and the potential for dietary interventions to reduce them, remain unstudied,” she said.

She added that goats could offer the opportunity to respond to changes in plant growth patterns due to climate change.

“With global average temperatures projected to rise, vegetation composition is expected to change dramatically.

“This could increase woody shrub coverage in arid and semiarid rangelands compatible with goat production, compared to cattle and sheep, as goats consume a diet typically comprised of 60pc browse, 20pc forage, and 20pc weed,” Assoc. Prof. Meale said.

Higher temperatures also decrease plant digestibility.

“Goats are more efficient in using fibre, nitrogen and water than cattle and sheep, and have been shown to have higher rumen digestibility of native browse,” she said.

Assoc. Prof. Meale said goats are able to tolerate high levels of tannins, found in such as acacia species, due to tannin-binding proteins in their saliva.

Other researchers involved in the study were Ph.D. candidate Morteza Moradi, Mingbo Ni, Dr Anne Beasley, Professor Louw Hoffman, all from UQ, and Professor Alex Chaves from the University of Sydney.

Dr Meale is following up with further research into methane emissions in goats – focussing on the effect of age, and another on pregnancy and parasites.

Read the research here: https://doi.org/10.1038/s41598-026-41322-8.