Cow is most commonly associated with Lord Krishna, who is usually depicted as a cowherd. Lord Krishna is also known as Gopala , literally meaning “the protector of cows”. The cow is also associated with Lord Shiva, whose vahana (divine vehicle) is a white bull, Nandi . A statue of Nandi is usually seen facing the main shrine in every Hindu temple dedicated to Lord Shiva.
Mattu Pongal (the third day of the harvest festival ‘Pongal' in Tamilnadu) is the cattle thanksgiving. People decorate and worship their cattle on this day.