A species should not be changed. Wiping out all the imperfections that make them animals takes away from being that particular species. You can't have a perfect species or else there is no room for improvement. Scientists can genetically modify animals in order to boost their food production by a significant amount; however, in doing so they are changing what the animals are naturally. It is not healthy when animals have to produce double the amount of milk or meat. It is not how they were made. Furthermore, although the food may come out in higher quantities, it may harmful to the human body, having harsh chemicals and high toxicity. It's not safe or fair to genenetically modify animals, and people should worry about what they are eating.