Rendering menu > Render > Render Elements panel > Add > Render Elements dialog > Hair and Fur

The Hair And Fur render element produces an additional image that depicts only the elements in the scene generated by the Hair And Fur modifier. This image can be used for compositing.

Note: The Hair And Fur render element supports only the “buffer” rendering method using the default scanline and mental ray renderers. Also, to use the render element with mental ray, be sure to turn on Render Scene dialog > Processing panel > Render Elements group > Render Final Image.