i am new to feeding hay pellets and cubes,but have just been forced to now use these. where i live there is a shortage of hay, and i have only 2 square bales left. i purchased 2 50lb bags of alfalfa pellets and cubes, 1 bag each. my mare is 21yr old,not rideable, and gets senior feed grain. my question is how much hay cubes/pellets do i give her?