It works the same way as for human food here, so the last sack I finished says "Best before 20/12/23" (NB we order dates day/month/year, so that's 20th Dec 2023).
I buy whole grains, so the sacks are dated 'best before' a calendar year on from date the sack was packed. There are much shorter...
It might be normal but it is not as clear and transparent as (to use your example) 3 Jan 2003. Can you convert, say, 25th of August into the so-called Julian day without using a calculator? (the real Julian calendar has nothing whatsoever to do with the poultry feed dating system)
If you want to stick with commercial poultry feed, I'd buy a bag of something that is transparent about its production date and doesn't require insider knowledge to work out how old it is.
In the meantime, if your birds are starving, I'd offer, if you have them, some milk-soaked bread, some...