White leghorns, red seal is a protein additive and yes only scratch before then and they were laying. I don't know how old the older hens are they were a gift. The younger ones were spring hatch. I live in southeastern Okla. and had warm weather until this past week.
Well there you go. You discovered the problem. It is hard to keep leghorns from laying eggs but since they are being nutritionally deprived by feeding only scratch, it was inevitable that they would play out early.
They need 90% of their diet to be chicken feed of some kind.
Right now they have a variety of mineral and vitamin deficiencies and before you started the red seal, they were deficient in essential amino acids.
A neighbor ran into me at the feed store and wanted to buy hens from me. When I asked why, he said his were broken because they quit laying.
I asked what he fed them.
He said, "scratch".
I said, "yeah but what else?"
He said, "just scratch".
I said, "you're starving them".
I told him to buy a bag of chicken feed and stop scratch altogether.
They resumed laying in about a month or more and they've been fine ever since.
Scratch is a good source of energy but very poor for providing nutrition.