"There was widespread support for animal welfare in Nazi Germany[1] (German: Tierschutz im nationalsozialistischen Deutschland) among the country's leadership. Adolf Hitler and his top officials took a variety of measures to ensure animals were protected.[2]
Several Nazis were environmentalists, and species protection and animal welfare were significant issues in the Nazi regime.[3] Heinrich Himmler made an effort to ban the hunting of animals.
[4] Hermann Göring was a professed animal lover and conservationist,[5] who, on instructions from Hitler, committed Germans who violated Nazi animal welfare laws to concentration camps.
In his private diaries, Nazi Propaganda Minister Joseph Goebbels described Hitler as a vegetarian whose hatred of the Jewish religion in large part stemmed from the ethical distinction this faith drew between the value of humans and the value of animals; Goebbels also mentions that Hitler planned to discourage slaughterhouses in the German Reich following the conclusion of World War II.[6]"
As for why Hitler invaded USSR, you can hear Hitler explain it here: