Marts are to return to online trading only under the Level 5 coronavirus restrictions announced by the Government on Wednesday evening.
Mart sales are to be held online only and marts can match stock between buyers and sellers.
Farmers selling stock at marts are to revert to the drop and go system, dropping animals off and leaving.
Buyers will be able to inspect stock in pens at marts by appointment only, Government has said.
"The following services relating to agriculture, horticulture, forestry, fishing, animal welfare and related services [are deemed essential]:
“Marts held online with arrangements to facilitate weighing of animals, matching of stock between buyers and sellers, drop off of animals and buyers inspection of stock in the pens by appointment.
“Bidding process is online only,” the Government said on Wednesday.
Farming remains an essential service under the Government’s Level 5 restrictions.
That includes farming, farm labour, farm relief services, forestry, AI services and fallen animal disposal.
On Wednesday night An Taoiseach Micheál Martin said that in the week before Christmas, about 5% of tests were coming back as COVID-19 positive.
"Yesterday, 18% of those tested were infected with the disease.
"Over the last seven days, more than 8,000 cases have been confirmed. That is a 61% increase on the previous week.
"This latest surge is different to the second wave. We are seeing rising incidence of the disease across all age groups, especially those aged 19-24 and a very worrying increase among those aged 65 and older," he said.