Was this a proper way to slaughter a cow?

I live in a small town with a few farms. Right behind my house is a farm that raises sheep and cows. These cows are some type of highlanders, very hairy with long horns. I am aware these cows are raised for beef but I have some major concerns about the way it was executed. This man took out his shot gun ( please note that I could see this from my back window ) and right in the middle of the field around all of the other 15 cows shot it dead. This was very upsetting to see. Was this a humane way to do this? Could he have comforted it by letting it sit down? Am I crazy or was it wrong to do infront of all other cows? Thank you