I dont render mine with a background, it looks stupid, unless I make my own background with props, then I render it in black. Or, render it images and do layers later. The only way to do animation is to storyboard it in Poser.

In animation, render background first, then foreground, then the main character by themselves, then layer it, in Gimp paint program, this is what I do. Its much faster than sitting and waiting for the entire animation of 5 hours or more to finish.