Sudden death occurs as a result of poisoning or nutritional deficiency. poultry are very sensitive to aflatoxin poisoning. it is advisable to always buy poultry feed from reputable feed companies. if you are making your own feed at home never use discarded maize otherwise reffered to as "muozo" or store your feed in places that they can get molds. use clean maize. remember poultry always scavange around for feed especialy in free range and they will never consume rotten maize. should this rotten maize be ground and mixed with clean maize without incoporating toxin binders, the birds will consume the toxins leading to sudden death. chemical poisoning from rat baits too could cause sudden death. certain species of mushroom too are fatal if consumed by birds(mycotoxicosis. with all those remeber too that fowl typhoid has characteristic sudden death. kindly check on vet pasting incase of fowl typhoid.