High condensed tannin (HiCT) white clover

AgResearch scientists are working with partners to genetically modify white clover to boost the level of condensed tannins present, offering significant environmental and farming benefits.

Background

High Condensed Tannin (HiCT) white clover has been modified to boost the level of condensed tannins present. Condensed tannins occur naturally in the flowers of white clover and in other species such as grapes, tea and many other components of the human diet. In white clover they offer significant promise for reducing environment impacts from livestock farming while improving both animal health and production.

This forage has traits that benefit greenhouse gas (GHG), sustain higher milk yields, enhance meat and fibre, improve reproduction, aid pest mitigation and animal welfare.

Predicted benefits

Increased animal health
Fewer plant pests
Reduced losses to the environment
More milk and meat
Increased animal reproduction
GHG’s down by 5-10%
Methane reduction > 16%
Reduced N leaching and N2O
Bloat reduction
Enhanced milk yield 10%
Increased live weight gain 30%

Creating impact

AgResearch scientists are working with partners PGG Wrightson Seeds and Grasslanz Technology to genetically modify white clover — an important component of pastures in New Zealand — with a gene taken from another species of clover to enable expression of condensed tannins in the leaves of the white clover. The modification made by the scientists essentially flicks a “molecular master switch” which increases the condensed tannins content to meaningful levels in white clover leaves.

The results seen to date in containment in New Zealand suggest reductions in methane emissions; and nitrogen leaching, in excess of 15 per cent are potentially achievable. Consumption of the white clover with increased condensed tannins is also expected to reduce the occurrence of a condition known as bloat that can be fatal for both sheep and cattle. It may also reduce the internal parasite burden for livestock.

Into the future

In addition to the modified white clover bred and grown in contained conditions in New Zealand, three years of field trials have been completed in the United States where regulations controlling the testing of genetically modified plants differ to those in New Zealand. The levels of condensed tannins expressed in the HiCT white clover grown in USA was consistent with what was seen in the plants grown in containment in New Zealand.

Subsequent cycles of breeding and growing in containment in New Zealand have demonstrated that modified HiCT white clover with commercially acceptable yield and persistence can be generated. Permission has now been granted for further field trials in Victoria, Australia, for a period for up to four years, and the first field trial was recently planted.

Further steps will see selection of plants for seed multiplication in Australia, as the partners look ahead to animal feeding trials and the potential for commercialisation of the HiCT white clover in the next few years.