Please don't. I understand being concerned about feed quality. I understand wanting to do best by your birds. But if you are going to pick an off the shelf feed intended for another animal, particularly long term, goat feed is probably the worst choice you can make of what's frequently on the shelf. Short term, nutritionally its no better on average, and usually worse, across a host of nutritional measures.
If the evidence out there is enough to convince you there is a problem with Producer's Pride, Dumor, or Purina, feed Nutrena - it’s made by Cargill. They have their own supply chain, factories, warehouses, etc. and whatever you choose to buy, CHECK THE DATE CODE. Old feed is not the manufacturer's fault, but that doesn't make it less of a problem.