U.S. President Donald Trump has indicated he intends to target Australian beef imports as part of his anticipated “Liberation Day” announcement on comprehensive tariffs.

“Australia bans — and they’re wonderful people, and wonderful everything — but they ban American beef,” he stated on Wednesday (Thursday AEDT) during a news conference at the White House in Washington DC.

“Yet we imported $US3 billion of Australian beef from them just last year alone.

The most common way the disease is contracted is from eating infected tissue.

In the United States, parts of a cow that are not eaten by humans are often ground into a powder and often used as cattle feed.

This means American cows are sometimes eating the parts of other cattle that could carry mad cow disease.

That then puts those cows at risk of developing the disease, which could then be passed on to humans that eat them.

Stocks fall after Trump announcement

US stocks tumbled in after-hours trading as President Donald Trump delivered remarks at the Rose Garden and unveiled sweeping tariffs.

Dow futures tumbled 256 points, or 0.61 per cent. S&P 500 futures slid 1.69 per cent. Futures tied to the Nasdaq 100 fell 2.54 per cent.

Stocks, which had risen prior to Trump’s tariff announcement, began to decline as Trump disclosed his administration’s strategy for implementing tariffs.

Exchange-traded funds that track the major stock indexes also tumbled in after-hours trading. An ETF tracking the Dow fell 1.1 per cent, while an ETF tracking the S&P 500 slid 2.2 per cent and an ETF tracking the Nasdaq 100 slid 3 per cent.

Meanwhile, the most actively traded gold futures contract in New York briefly rose above US$3200 a troy ounce, a record high. Gold is up more than 20 per cent this year and just posted its best quarter since 1986. Gold is considered a safe haven amid economic and political uncertainty.