In the past week, local beef finishers have been able to obtain prices up to £120 per animal better by exporting their cattle to Great Britain, rather than sending them for slaughter in local meat plants," he added.
"Local farmers should not accept bad prices from local processors. In the past week prices being offered by local meat plants have been almost 40 pence per kilogram lower than what's available in other parts of Great Britain.
"This price differential is a disgrace and is totally unjustifiable.
"Our cattle are produced to the same standards and are primarily going into the same UK retail market.
"Our traceability system is supposed to be second to none, and it is unjustifiable how our cattle are being valued so much lower.''
William Taylor called on local farmers to consider the export option, or the live trade, where stronger prices are available.
The Union representative also pointed out that some commentators have tried to talk down beef prices because of lower consumer demand.
William Taylor added: "There's not much sign of a credit crunch in GB, with prices for beef £120 better than locally."
The UFU has also highlighted the fact that slaughter figures so far this year indicate an eight per cent decline in total NI cattle slaughtering and an 11.5% decline in NI prime beef slaughtering.
William Taylor added: "In the past week, while quoted factory prices in NI have fallen yet again, there are clear signs that the GB market has strengthened. Prices for cattle going through the NI live market have also increased considerably whilst cattle going for direct slaughter in GB are making up to £120/head above the deadweight price here in Northern Ireland. This continued differential is unacceptable and is doing further damage to local beef production, which is already on its knees.''
Responding to these comments, Northern Ireland Meat Exporters' Association (NIMEA) chief executive, Phelim O'Neill, told Farming Life that a snapshot comparison of some prices in a particular week did not accurately reflect the overall differential between Northern Ireland and Great Britain, where the beef market is concerned.
"At the present time the prices available here in Northern Ireland compare quite well with what's available in Great Britain, when one takes all the classes of finished cattle available locally into account. This includes young bulls, heifers steers and cows."
Phelim O'Neill went on to point out that local redmeat processers are not in the process of 'fleecing' beef and lamb producers.
"All of the factories opened their books to the McKinsey team responsible for compiling the Redmeat Taskforce report," he added.
"This exercise confirmed that processers in Northern Ireland are making a moderate profit only. It is a fact, however, that almost all of our meat plants are highly dependent on UK supermarket trade. These outlets are not suited to cattle that are Fat Class 4 or over. It costs the farmer a lot of money to put fat on and more money again on the part of the processer to take it off, once the animal has been slaughtered."
He said: "It's up to the farmer to make use of every market opportunity available to him. If there is a better return for cattle in GB, then he would be foolish not to export animals that best suit this outlet. At the end of the day the market is king and this principle holds equally for processers and producers.''