So the EU can have no general objection to beef imports from Argentina on standards\health grounds.
I suspect that they can, eg, growth hormones are in use in Argentina:
"The use of hormones to increase weight gains and dressing percentage is common
practice in North American feedlots, also in Australian and South African....... These measures, as well as the import of beef produced with the help of these substances,are banned in the EU; the meat imported to the EU must verifiably be produced without the use of HGP."
Argentina has for a long time had a quota for beef imports into the EU ( provided standards met). But the Argentine beef industry went through a decade of steep decline and wasn't always able to meet its existing (relatively small) quota. I understand it is now recovering - but to nowhere near historic levels.
Brazil is a much bigger producer - but, as galway_blow_in has said, it has a history of much more questionable standards and the enforcement of agreed standards. It is not only the EU that has had major concerns about their procedures - also the US, China and others (See here, for example: ).
Probably quotas will increase in future trade deals. But it will most likely be dependent on each of the countries introducing verifiable tracing systems for animals and reliable national enforcement and inspection. I can't see hormone produced beef being allowed in the EU any time soon so, to keep a level playing-field, this section of their production will have to be segregated.
Feedlots are allowed in the EU. But hormones are not. And registration of animals and traceability systems are required. There are also animal welfare standards. I think there have been some issues in regard to intensive production methods in Spain, resulting in EU intervention.
Feedlot production is increasing worldwide. Over 95% of South African beef is produced in feedlots. One caters for approx 150,000 cattle and is reputed to be the biggest in the world. Perhaps not surprisingly, there has been a corresponding increase in consumer demand for grass fed beef (and organics). All the more reason we should hang on to ours.