On Gopashtami day, Nanda Maharaja performed a ceremony for the cows and Krishna (and His friends) in Vrindavan, as He reached the pauganda age. This was the day Nanda Maharaja sent his children Krishna and Balarama to herd the cows for the first time. It was a celebration meant only for men and boys. As Srimati Radharani and Her friends wanted to enjoy the fun, and because of Her resemblance to Subala-sakha, She put on his dhoti and garments and joined Krishna. The other gopis joined in too.

Devotees remember this sweet pastime on Gopashtami day. This is a very special day at Mayapur as we are fortunate to have darshan of the most merciful lotus feet of Srimati Radharani and Her sakhis.

Go-puja is also done on this day. Devotees visit the Gosala, bathe and clean the cows and the Gosala. The glories of the cow and her protection are discussed by senior devotees. All of them feed the cows and partake of a feast near the Gosala.

Source: Mayapur.com