Calls have been made for marts to return to in-person trading following an IT glitch at the weekend that saw the cancellation of several online sales.
The Mart Managers Association has said marts can operate safely and adhere to social distancing.
Spokesperson Eimear McGuinness said farmers are angry and want mart sales to return to in-person trading.
Several sales at the weekend were cancelled due to an IT glitch, which meant that online trading could not take place.
After several hours of an outage some sales did operate on Saturday, but thousands of animals were left standing without feed for hours.
All mart sales are now held online due to Level 5 restrictions, meaning people bid for animals that they view on video streamed from marts.
However, ICOS, the national co-operative marts body said mart operators are "proving their metal and staying resilient".
Ray Doyle from ICOS said: "Since the first lockdown, when effectively the sector was shut completely and only had a limited tendering system in place to facilitate trade, we are only back 9.6% overall year-to-date (YTD) - at 1.275 million cattle as opposed to 1.4 million last year.
"However, when you analyse the trading pattern of the last three months in particular, August was up 43%, September up 20% and October up 6.7% up to the 25th of the month and it's not finished yet".
Ms McGuinness said it is "almost impossible" for marts to operate online only sales, due to issues with broadband and many farmers do not have smart phones to enable them to trade online.
Independent TD Denis Naughten has claimed that Government's own Broadband Plan identifies that 40% of marts across the country have a poor broadband service which requires upgrading.
He said: "With 40% of marts failing to have decent broadband then the online-only sales of stock needs to be reviewed, particularly with large numbers of weanlings and store cattle coming to market at present".