Nandini Navami is a vrat dedicated to Nandini, the sacred cow. In 2012, Nandini Vrat date is December 21.
Nandini Navami vrat is observed on Shukla Paksha Navami in Margashirsha Month as per all Hindu calendars.
Nandini is believed to be the daughter of Kamadhenu. Kamadhenu granted Nandini to sage Vasista.
There are several vrat dedicated to Cows and cattle in Hinduism. Gopadma Vrata, Bail Pola, Nandini Vrat, etc are some of the other festival dedicated to Gomata.