in our country you can buy everything for any animal.
if they needed or not..depents on the owner
some overload their animals and some give to less.
i do not know what is perfect. I watch my horses and reed as much as i can when i think they need someting. Before i give it, i'll read and read..and then buy it yes or no.
Sometimes for horses is only grass not enough and they need some more. Then you have to find out what they need.
and that is sometimes a long way...
and the next problem is do they wanna eat it
i have very difficult eaters