Tar,
We regularly milk 180-200 liters/day on 1 hectare with 12 cows in rotational grazing management of 22 pickets of 450 M² each. It is done in many tropical countries, Costa Rica included.
It is obvious that you know what are you talking about : crossbreeding, rotational grazing, wich are necessary tools for good results.
Still I am confused......
I am in proces of buying a farm here, so I had to do lots of math. My interest is in goats but most data is about cows and here is what I found:
H igh quality feedstock daily intake is 2-3 % body weight on DM(dry matter) basis. 2% for dry cows and 3% for cows in lactation(20 lbs.milk daily per cow). Assuming that 25% of animals are dry the average daily DM intake per cow is 2.75% body weight.
Averaga cow is 1200 lbs. So average daily intake is 33 lbs DM basis.
For 12 animals it is 396 lbs DM daily. That is 144540 lbs a year. (cca 65.6 tons)
Grassis have average water contents of 85%. DM is 15% .
So for 144540 lbs DM GM(green matter) yeld has to be 819060 lbs or
372 tons/ha !
Is it possibile? Even in tropics ?
For instance sorghum is tropical & subtropical hight yelding crop. But recor crop is achived in China 135 tons GM/ha, and just a little less in Europe (Croatia) 130 tons/ha. Intensive tillage and very intensive ferilisation (manure + NPK) + beter rain distribution since there is no rain or dry season.
And even if 372 tons/ha is possibile, that would be enough only in theory since in grazed fild effective yeld is smaller.