How do you fatten up the Cow with grass?

In the Op-1 manual, the Cow filter (what does “CWO” stands for actually?), shows an instance where a bundle of grass can appear in the filter.

What has to be done to get the grass to appear? I’ve tried setting the filter to the parameters in the image already.

Thank you.

Screen Shot 2015-06-30 at 2.30.51 PM

Probably just a prototype screenshot that accidentally made its way to the manual(?)