Mash for chickens is ground up grains like corn, wheat, rye or their byproducts or Seeds like millet. Legumes like soybean meal, field peas. It's sold as Laying Mash as I remember my mom buying Blue Seal brand back in the sixties and seventies. You can probably find mash at an independent farm and feed. Blue Seal still offers Mash, they call it Meal. If you can find a Farm and Feed that carries it.
Most chicken feeds today run the above mash through a machine to produce a Pellet. Crumbles are made from Pellets. They are run through rollers to crush the Pellets.
Mash looks similar to the powder at the bottom of a bag of Crumbles or Pellets. Though not as powdery, more little bits of Corn and Grains in the Mash.
Maybe you were thinking of Scratch Grains in Winter to help keep Chickens warm. Some use Whole or Cracked corn. I feed Scratch Grains mid-morning year round as a Treat.
I also make them a wet mash with Crumbles.
GC
