While campaigning for his party in the crucial state elections in Bihar state, Mr Modi ridiculed a regional rival for saying many Hindus eat beef.
There are worrying reports that supporters of the BJP and right-wing Hindu nationalist Rashtriya Swayamsevak Sangh in the state have launched a virulent campaign against cow slaughter and beef.
Although the government's own animal census shows that the cow and buffalo population has grown - a 6.75% increase between 2007 and 2012 - and cow slaughter is banned in most states, there is hysteria being whipped up that the bovine is under threat.