1. The most important thing is you must not rely on words of any seller either from Australia or EU or the USA, and asked them for Genomic testing that is standardized certificate, a heifer having 2300 GTPI (genomic total performance index ) is same either from Australia,  EU, and the USA .if grown with same nutrition they would be given same results ,this is called standardization.

2. Moreover, there is Myth from cow sellers that we bring the cows from hot weather .so our cattle are more tolerant, it is only sale technique.

1. Human produce 300 BTU
2.18-liter cows 3000 btu
3.50-liter cow 6000 btu.

SO if you feel hot in shed than must realize your cows feel it 10 or 20 times more heat inside the shed.

Controlling does not mean tunnel only,  it means to have felt like 20 to 27 C on each cow level(microenvironment) with air change 1 minute. can best be achieved from insulation,  High-velocity fans, Exhaust fans,  foggers, and sprinklers.

3. Moreover now under the current circumstances on an avg break-even point is 25 liter in commercial farming around,  so we must have achieved 30 liters or 9000 liters per year.