With respect to kosher meat- generally speaking the main difference between kosher meat and non kosher meat with respect to something like Mad Cow is that sick animals DO NOT make it into the kosher food supply. They are not allowed to be used- they don’t make the grade, so to speak.
I don’t know if they are fed any differently in small companies- Hebrew National is now owned (along with most of the rest of the world) by ConAgra. I imagine the cows all eat the same stuff- they are just slaughtered diffeent;y and then soaked and salted to be kosher. Perhaps in smaller Glatt Kosher companies, the animals are not fed feed made with other animal products.
It’s always safer to grind your own meat, or failing that, to avoid ground meat from large operations that might contain thousands of animal’s parts in one big batch, making it harder to ensure that all the meat is frim healthy animals.