Correction, plowing paddy fields is done by water buffalos.... not cows. Modern western style farms are not plowed by cows but by machinery. Even if cows are used as in the traditional sense, they dont produce the immense amount of menthane produced now by cows raised solely for livestock.
As for cows giving us beef.... well beef is one of the most ecologically unsound meat to produce. The amount of land cleared to provide fields and amount of grain needed to feed them just dont add up. In addition, do you know why beef is so cheap? Heard of cow cities? Yes virtually cities where cows do nothing but eat grain that is not meant for their stomachs pumped with antibiotics to ensure they dont fall sick and sleeping on their own manure in pens devoid of any vegetation.
As for milk, do you know why a cow produces milk? Simple because it has babies, anyone askes where the babies go? Well a cow is made pregnant, the calf is delivered and before it can take any precious milk, it is taken away and fattened on an artifical diet till ready for slaughter and sold as veal. Result is heart rending cries of cow looking for calf and calf looking for mother.
In my opinon, modern day cow rearing is one of the biggest sins of humanity. In the quest for profits, inhumane methods are used.
Want to find out more, just go read books like Food Inc and a vegetarian dilemma.
I m Doing it ..