Where did this latest BSE case spring from? There are three possible answers.
Because this cow was only born in 2010, it makes the likelihood of feed contamination incredibly small, but this is still the prime target of the department's investigations.
Despite a ban on meat and bonemeal in 1999, department officials readily accept that this measure was not really enforced until 2001, when people began to understand the risks of cross-contamination in feed.
However, BSE cases continued to crop up in animals that were born after this period, usually followed by discoveries of feed that had been lodged in the corner of a silo somewhere that had belatedly made its way into the feed chain.
Another theory could be that the mother of the cow may have passed the disease onto her calf, which some scientific studies suggest is possible, if very rare.
But on the basis that this is a possibility, and that the mother of this cow was imported from abroad, it is possible that she came from a region where controls over feed were not as tight as here.
Equally plausible is the suggestion that this is a case of 'atypical BSE', as opposed to the 'classical BSE' that is acquired by bovines that eat contaminated meat and bone meal when they are calves. Atypical BSE occurs sporadically among cattle and, although extremely rare, approximately 40 cases have been discovered, according to UCD's Associate Professor of Human Health, Pat Wall.
"We only started discovering these cases when we had robust testing systems in place to pick up classical BSE," said Prof Wall.
"The first case was identified in Italy in 2004 and cases have subsequently been found in Canada, Germany, Switzerland, Norway and Brazil.
"Controls on animal feed started in Ireland in 1997 so nobody can understand how an animal born in 2010 could have had access to contaminated feed. Molecular typing is under way to determine if this is the case," he said.
The former head of the European Food Safety Authority also pointed out that the latest case was a reflection of the strength of our surveillance systems.
Beef farmers will have other questions weighing on their minds, namely the impact the discovery will have on the trade. The short answer is that nobody is sure, but cattle agents said that their phones were busier than usual yesterday, indicating that some panic selling by farmers fearful of a price fall was already under way.
In theory, the latest case shouldn't have negative effects on the trade since it merely means that Ireland's BSE status as a 'controlled risk' region will remain for another six years.
We have already made good progress on accessing new markets such as the US and China, despite being lumped into this second-tier group that includes the likes of Britain and France.
But the reality is that we sold our story to the likes of China partly on the basis that we were on the cusp of BSE-free status. We desperately want to be able to go toe-to-toe with our biggest competitors like Brazil and Australia that are both BSE-free. We are just going to have to be more patient now.
The Department of Agriculture's Assistant Secretary, Brendan Gleeson, said his officials had proactively contacted administrations in key export markets to flag the case in advance of media coverage.
"It's been 2005 since the last time that we had a five year-old animal testing positive for BSE, so we are hugely disappointed, but we believe that it shouldn't knock anyone's confidence," said Mr Gleeson.
The discovery also has implications for farmers who have been lobbying hard for the removal of restrictions on cattle over 30 months of age, brought in after the BSE crisis, going into premium contracts in supermarkets.