Cow's milk is a very satvik food (mode of goodness, per ISKCON terminology).
But it is satvik if and only if the cow's OWN calf drank from the mother first.
It is satvik if and only if the cow is protected in its olden days when it can no longer give milk.
It is satvik if and only if the first 10 days after birthing colostrum milk is given to calf only, not for human consumption.
Basically, we must not steal from the cow, it must be a mutual give & take. There are many restrictions for a cow's milk to be very satvik (native indian breeds like those in brindavana, no artificial insemination)
Source - Ahara Niyama
There is a saying:
a woman past her beauty, a soldier past his strength, and a cow past
its milch-days must not be cast aside
i.e. don't adopt use & throw mentality. Because the same fate may befall you one-day, when you're feeble and sick, your own children may not care for you (karma will find its way).
Unfortunately nowadays in Kali Yuga, it is very hard to find such facilities, even in India. So I try to buy organic milk, or from goshala or local farmer whenever possible.