The figures have also sparked concerns that the nation's ewes - adult female sheep - are ageing, as farmers focus on breeding sheep for the dinner plate rather than for wool.

Ten years ago the Australian sheep flock was 115.5 million; in June this year it was 71.6 million, a decline of 38pc in a decade.

The last time the nation's flock was so low was in March 1905, when there were an estimated 65.8 million sheep.

Industry leaders say the reasons for the fall include the drought and associated feed costs, the fall in wool prices, farmers swapping from wool to meat sheep and the growth of cropping in Victoria.

Agricultural consultant Mike Stephens, who is based at Yendon near Ballarat, said he believed the population of Australian ewes was ageing, but this could not be quantified.

"At the same time as we're getting a diminishing number of sheep, we have to be getting an ageing sheep population. Because if you stop breeding replacements, but go on using the females that you've got in order to just breed your meat sheep, one day you'll turn around and all of the girls are too old to go on breeding," he said.

Mr Stephens said he was often asked by farmers whether or not they should keep sheep, and his answer was yes. In the long term the profit from a well-run, dual-purpose sheep flock (wool and meat) was comparable to that from cropping, he said.

Victorian Farmers' Federation president Andrew Broad said that two of the main reasons for the fall in sheep numbers were the drought and the "protracted downturn" in wool prices. "Even myself, I've gone from running wool sheep, now I don't run any wool sheep, I run prime lambs (for meat production)," he said.

"Unless we see a return in wool prices I think we'll continue to see a decline of wool sheep. I think it'll be a gradual crawl back in meat sheep; those numbers won't decline, but they don't jump ahead very fast either," Mr Broad said.