Whether its chicken, lamb, goat, turkey; stunning means they were given shock by electricity or shot by bullet. Hence inflecting painful trauma to the animal that in-turn hold blood in their cells. this is one of the reasons that meat is not unhealthy and the rotten blood cells in the meat cause different diseases. This is also Haram to eat but sold widely as Halal. For example, a cow which is stunned and slaughtered will release approximately 1 bucket of rotten black blood whereas non-stunned hand zabiha fills 2-3 drums (not buckets) of red pure blood. This explains why the stunned meats are causing medical issues in humans and also explains why stunning is Haram.