CockadoodleMoo.org

"The Holocaust & the Henmaid's Tale: A Case for Comparing Atrocities" by Karen Davis is a short (and expensive!) book from 2005 that gathers information from many different writings on the Holocaust, the Nazis' treatment of animals, industrialized killing of animals for food, and the controversies surrounding all of the above. It's readable and insightful. The simplest case for making a comparison is that Holocaust survivors routinely described their ordeal as being "treated like animals", implying that animals are treated similar to those in concentration camps. But there's a lot more behind the controversies, such as the genesis of the name "The Holocaust", how it's decided what's a holocaust, whether using the Holocaust as an analogy denigrates those who went through it, etc. Very worthwhile for those who are interested in the use of the Holocaust analogy in the animal-rights movement. Here's an excerpt, taking out the book citations for the quoted passages:

In modern industrial society, the transport and killing of animals takes place mostly out of sight, though not for the people who do the work — yet how many workers identify with their victims, or become vegetarians? Virgil Butler, who worked in a Tyson chicken slaughterhouse for five years, said of the chickens, paralyzed with electric shocks before having their throats cut, "Their muscles don't work, but their eyes do and you can tell by them looking at you, they're scared to death."