In the past when I have needed to simulate an effect similar to what you describe what I did was to have the animation effect set up on a separate slide entirely. So I had one slide as the menu slide and clicking items on that slide would jump the user to an intermediate slide that shows the effect (this slide was usually only a second or so in duration) and then as soon as that slide ended, it continued to the slide that started the relevant content section.
So the trick here is that although the content starts on the slide AFTER the animation slide, you point the menu object to jump to the animation slide, not the content slide.