Australian lamb exports will be defined in the same way as New Zealand's animals, ending a competitive advantage for farmers across the Tasman.
The federal government will amend Australia's export laws to change the definition so animals with two permanent incisor teeth are considered lamb.
As long as the teeth are new and have not started to wear, exports will be considered lamb, bringing Australia's definition into line with the NZ classification.
"After decades of discussion, the time for talk was over. This is a simple common-sense change," Agriculture Minister David Littleproud said.
He said the move would mean farmers could sell more lambs toward the end of the growing season, boosting export opportunities.
"It will be easy for growers to see when a lamb becomes a sheep - when there is visible wear on the incisors," Mr Littleproud said.
Lamb had previously been considered to have grown into the less lucrative hogget or mutton as soon as incisor teeth were visible.
Research by Meat and Livestock Australia found no difference in eating quality between lambs immediately before incisor teeth and immediately afterwards.
