When is the cow worthy of protection? When should cow protection be rejected?

Cow is worthy of protection only in as much this serves humanitarian and national interests.
Animals such as the buffalo, cow and trees which include banyan and pepal are useful to man. This is why we are fond of them. To that end we might even consider them worthy of worship. Their protection, sustenance and well-being is our duty. In that sense alone it is also our dharma! Does it not follow then that when under certain circumstances, that animal or tree becomes a source of trouble to mankind. It ceases to be worthy of sustenance or protection and as such its destruction is in humanitarian or national interests and becomes a human or national dharma? 

from Portraits of Society and Stories of Savarkar.

The concept of sacred grooves is worthy of mention here. A area of a forest is marked out and animal grazing and farming is prohibited on that land. This not only maintains the ecological balance of that village but also replenishes water table and prevents soil erosion. Such is the foresight and wisdom of our ancient rshis!

When humanitarian interests are not served and in fact harmed by the cow and when humanism is shamed, self-defeating extreme cow protection should be rejected.

A substance is edible to the extent that it is beneficial to man. Attributing religious qualities to it gives it a Godly status. Such a superstitious mindset destroys the nation’s intellect.