Diwali - the Hindu New Year - is a five-day festival. Diwali in Krishna Temples is often celebrated as a day of feeding and venerating cows.
Diwali Festival in ISCON
In ISCON devotees of Krishna celebrate the actual day of Diwali, on
which Lord Ramachandra returned from exile, and on which Lord
Krishna performed his pastime of breaking the pots of yogurt and
letting himself be bound by Mother Yashoda. According to them
believe that Diwali can be observed by illuminating hundreds of
candles in different parts of the temple, and offering sanctified
food to the Deity. The inhabitants of Ayodhya observed this ceremony
while Lord Ramachandra was in exile, away from His kingdom.
Diwali celebration in Nathdwar
In Nathdwar, the Diwali celebration is done by a day-long feast for
cattle called Annakoot. The reason for this special place
given to the cow lies deep in the religious consciousness of
Indians.The sacredness of the cow goes back to the myth of the churning
of the cosmic ocean by the gods. Of the 14 `jewels', which the
ocean gave to the gods, Kamadhenu, the celestial cow, was
one. She was venerated as the mother of the universe. The celestial
cow is also called Surabhi or Nandini, the giver of
joy and plenty. A cow is the constant companion of Krishna.