Understanding methane-reducing tannins in enteric fermentation using grape marc as a model tannin source
Methane from ruminant animals contributes approximately 10% of Australia’s GHG emissions. There is potential to reduce these emissions by supplementing livestock feed with tannins or tannin-containing feed, which have been shown to reduce the production of methane. Grape marc has been suggested as a possible source of tannin able to be used for this purpose. This project applied the AWRI’s existing expertise in tannin chemistry to gain a thorough understanding of the tannin in grape marc, and apply this knowledge to achieve reduced methane emissions and productivity improvements in the livestock industry. Funded by the DA through its ‘Filling the Research Gap’ program, this project was managed by Meat and Livestock Australia as part of the National Livestock Methane Program.
Use as a feed additive
When grape marc was compared with maize silage (a common feed additive) over a 100-day feeding trial, no significant differences were observed for feed intake, feed use efficiency and daily live weight gain, showing that grape marc can be used in feedlots without detrimental effects on animal performance. The effects on daily methane production were modest (consistent with previous studies), with observed suppression likely due to additional oil content in the feed from the inclusion of grape marc.
Spreading the message
A series of case studies were developed in conjunction with businesses that use grape marc in their feeding regimes, focusing on practical aspects as well as reasons for using grape marc as a feed additive. The studies span both dairy and beef cattle producers, and promote the effectiveness of grape marc with the aim of achieving wider industry uptake. The case studies represent the final activities in this project. A final report will be submitted to the DAWR early in the next financial year.