It was an ordinary grade hamburger meat for most of the chains.
也就是说,大多数连锁店做汉堡用的肉都是普通的肉。
英语百科
O-grade
(重定向自Ordinary Grade)
The Ordinary Grade (commonly known as the "O-Grade") of the Scottish Certificate of Education is a now-discontinued qualification which was studied for as part of the Scottish secondary education system. It could be considered broadly equivalent to the old English O-Level qualification and is the predecessor to the Standard Grade qualification.