After living across the road from a non-devotee dairy for a couple of years, I saw first hand how non-devotees treat cows, it was hellish and very disturbing to anyone who has conscience given to them by Srila Prabhupada.
The babies, male and female, were rounded up and sent to the meatworks when they were only a few weeks old. The cows continued to produce milk for their babies, and be exploited for this milk before becoming pregnant and going through the same process again. The cows would cry out in distress for their babies for many days after they were taken.
In a country like Australia, it is not possible to turn these cows out on to the streets to look after themselves. In India they have a totally different approach to cows, and it may be acceptable to use the milk, but in the West the average household doesn't have a cow in the back yard, and if they did, within a few years there would be a dozen cows in the backyard, ie: the cow, her calf, the calfs calf, and so on. Because cows have to keep having a calf to produce milk.
I would liken it to eating meat. The cow has to suffer and its baby has to die. That's the harsh reality of drinking milk in the western world. We have to live in the present moment and make decisions based on the circumstances that are presented before us.The truth is drinking milk obtained from these cows is blood milk. There was one argument that veganism does not protect the cow, we could take that a little further and say neither does vegetarianism. It is an ethical and spiritual choice, if Krishna says love the cows, then we can't be involved in the perpetuation of the calf killing system. Anyway, doesn't Krishna say a leaf, fruit, flower, or water? Veganism may not stop the killing of the calves, but you are opting out of the cycle and that surely has to be the most spiritual choice.
One thing I have noticed is that non-devotees are becoming increasingly more intelligent at knowing what Hare Krishnas believe in. The above arguments are constantly raised by vegan non-devotees and the meat eaters. Remember how hard it was to move out of the comfort zone and give up meat? Thats why there are all those meat substitutes. Let's try to go the extra step and give up blood milk.