Like an organic label where you cannot tell if the food item is indeed organic or not, you can never tell how a cow was raised for that beef. Depending on the ranch, cows can be fed anything nutritious aside from ordinary grass or silage. Over here, cattle is sometimes fed with mulberry leaves and I've heard that they also give corn (although I still have to confirm this). Now, with that beef you are saying if it was grass-fed, perhaps you just have to ask the vendor if he knows about it.
you can tell the difference if meat is well looked after and well hung and well butchered,
But not if grass fed, which depending on who you ask can mean different things.
Consumer: The cows have been fed on grass, as seen growing in the fields. Not possible in this day and age to manage all year round.
Butcher/P.O.S.: The cow has been fed only grass, all year round. This will include silage(possibly hay), with artificial feed. Beef nuts, grain etc.
Farmer: The cow has been fed only grass, all year round. This will include silage(possibly hay) with no artificial feed. Beef nuts, etc.
In all the above the animals will have spent the better part of the year outside.
To confuse matters slightly, on the organic side.
Pit silage: Whilst slightly easier on the environment(less plastic used) isn't organic feed. Because of what is poured over it at various stages and before the final plastic covering is placed over it. The pit size determines how often. The run off is highly corrosive as well.
Baled silage: Usually black/Light Green plastic used for the covering on round bales, is classed as organic feed. Nothing being added to it prior to wrapping. Other than the cords/netting to hold it in place. But a larger amount of plastic(non bio-degradable) to get rid off. 25 years on & the plastic remains in the "building" set aside for it, four walls and a bit of a roof. As good as the day it went in.
Both are grass, but only one is organic.
And the consumer has very little chance of knowing if the grass it was fed on was organic or not. Nitrogen fertilizer usage will instantly remove the organic label from it, as will any on which the slurry from animals fed on anything other than organic products has been spread.