The Force raytraced camera clipping attribute is available in the Render Settings: Options tab so that, when enabled, the near and far clipping planes are respected for primary rays shot from the camera when rendering with mental ray for Maya.
However, this attribute should be used with caution in combination with lens shaders bending eye ray directions (for example, fisheye-style shaders), as it may lead to unexpected results: clipping is done based on the camera only.
The attribute is disabled by default. You can enable this option via the Performance section of the Options tab in the Render Settings window.