One of the things that goes along with the shift from agricultural to urban in this country is that the old sayings most likely make no sense to someone who has never been in a farm or rural environment. Take this product, for instance.
A lot has changed since 1886. I'm glad they decided to keep the slogan on the can for old time's sake. What it means is that when chicks first come out of the eggs, it is a little while before they 'scratch' - before they begin to use their claws to rake the bedding material. Chickens spend a lot of their time scratching up the soil for food, and probably that first scratching is an innate knowledge of what they need to do to survive.
So, for a product that promises not to scratch your sink, this is the perfect saying. There's a nice page about the company here.
I've read that more people in cities and bigger towns are raising chickens now, so maybe the saying will be better understood in the populace. I certainly didn't know what it meant until we began keeping chickens all those years ago. Incidentally, we have new chickens arriving in May. I've written about the experience here on the blog.