I don't know what a crn number is? But I live in Scotland, so it might be different. You need your cph number, plus a herd number for your goats, and a seperate herd number for the pigs. If you were to get sheep, you would need a seperate herd number for sheep too I think.
You don't need a herd number for the chicks, unless you have more than 20, and then you are supposed to register with Defra.
Beth