SB 10.6.19
yasoda-rohinibhyam tah
samam balasya sarvatah
raksam vidadhire samyag
go-puccha-bhramanadibhih
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Thereafter, mother Yasoda and Rohini, along with the other elderly gopis, waved about the switch of a cow to give full protection to the child Sri Krsna.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
When Krsna was saved from such a great danger, mother Yasoda and Rohini were principally concerned, and the other elderly gopis, who were almost equally concerned, followed the activities of mother Yasoda and Rohini. Here we find that in household affairs, ladies could take charge of protecting a child simply by taking help from the cow. As described here, they knew how to wave about the switch of a cow so as to protect the child from all types of danger. There are so many facilities afforded by cow protection, but people have forgotten these arts. The importance of protecting cows is therefore stressed by Krsna in Bhagavad-gita (krsi-go-raksya-vanijyam vaisya-karma svabhavajam). Even now in the Indian villages surrounding Vrndavana, the villagers live happily simply by giving protection to the cow. They keep cow dung very carefully and dry it to use as fuel. They keep a sufficient stock of grains, and because of giving protection to the cows, they have sufficient milk and milk products to solve all economic problems. Simply by giving protection to the cow, the villagers live so peacefully. Even the urine and stool of cows have medicinal value.