Can you get me the names of the all the horses you interviewed so I can confirm that they don't differentiate between biological sex and social gender roles, as humans do?
You only need to spend 10 minutes reading about gender diversity around the world to learn that the social status of "woman" and the biological sex of "female" are different things. And oocyte "production" doesn't have anything to do with it. There are LOTS of women who no longer produce ova—every post-menopausal woman, in fact. Some women NEVER produce ova (shocking, I know!) And lots of females who aren't women. For example: all girls (who also don’t produce ova until puberty). So, your “woman = female human, female is an eggcellcreating organism” definition has issues. Lots and lots of issues.
The problem with every biological determinist argument that seeks to anchor the social status of woman in the biological sex of female is a failure to acknowledge that the body is not a fixed, stable thing. It's constantly changing, over time and in relationship to its many environments. There is no universal human female experience that can be encompassed by the concept of "woman." And that’s because biology is not the sole basis for determining a person’s membership in the social class “woman.”
That particular "truth" is grounded in a great deal of empirical research in the sciences, social sciences, and humanities. Let me know if you need an recommendations for reading so you can learn that "truth."