Elephant grass farm size for cattle

[Henlus]

Serious cattle farmers grow their own grass instead of relying on free forages in bushes. In Columbia, elephant grass in 2.5ha maintained 35 milking cows producing an average of 15L milk per day. The grass was supplemented with 1kg of concentrate per 4kg of milk produced (i.e 3.75kg concentrate per cow). I guess this info can help someone estimate how much land is needed to grow grass for dairy cows.