We did our first harvesting. We used a killing cone, birds were not stressed. We let the chickens/roosters bleed out, maybe hung 5-10 mins. After cleaning the birds we put them in cold water for several hours, changing water frequently. Let them dry on a table for an hour or so and bagged them. We kept the birds in a fridge for 4 days before freezing but the rigour mortis did not pass. They are very tough. The birds were Brahman, my understanding is these are meat birds. Not sure what we did wrong. Help please.