I know for a fact that they used to teach that, and I think they still do, but that they don't mention it (at least not much).
That issue was the main objection I had to overcome when I finally gave in and became a JW. And my overcoming it was not getting an answer to it. I just put it on the back burner as I was told to. I was told to put "the truth" first, and I would get an answer to my question later. Of course, no JW could answer it at the time, and I never got an answer to it; in fact, the question grew in intensity over the years. I gathered vast evidence that made the teaching that animals didn't kill each other before the flood seem ridiculous.
I used to even gather evidence from Watchtower publications. For example, I remember an article detailing how a certain bird of prey has two sets of eyelids - one regular and one translucent. The article said that the translucent one was used by the bird as it was pursuing its prey; it enabled it to blink and not lose sight of its prey. 'Praise Jah for his marvelous design.' I was wondering why such an eyelid would be needed if animals weren't originally designed to kill each other?
Another article described a particular bird that lived in or spent a lot of time in reeds (the tall grassy-like plants). The article described how the bird instinctively swayed in sync with the reeds as the wind blew so it could blend in and avoid predators. 'Praise Jah for his marvelous design.' I was wondering why animals would need a defensive strategy if there originally was no "offense"?
So, really, it's not only all the evidence we in predators that makes the JW teaching seem ridiculous, but all the defensive strategies we see in nature also make the teaching seem ludicrous, for there would be no need for such if there were no predators.
I won't do it now because I was planning on starting a new topic about it, but I could list pages of evidence against the JW belief.