Killing for the sake of prolonging life happens all the time. Have you ever consumed meat? How about plants? They're all "God's" creatures, killed for our culinary pleasures. It's sad, but so is the fact that some people must make merely minimum wage despite clean living and having a good work ethic (although neither reality gets changed).
Now your slipping back into the enviro/communist mind set. You really are all over the board. Animal life is not comparable to human.
And you substituted "killing" for "murder", two very different things. You can't murder a animal, but you can murder a human.