Sales tax exemption on cattle feed

Hi

I am a cattle-feed manufacturer in Kolkata, West Bengal. In Kolkata, selling of cattle-feed is sales tax exempted i.e. no tax on sales of cattle feed.

Now, I want to import the same (Mustard Cake) from other states. My question is will I have to give a waybill for the same to the seller? Secondly, will I have to pay entry tax in West Bengal on the same / is there any tax on mustard cake being impoted from out of bengal ?

Regards

A