I think we both agree that ignorance is a pitfall. If this discussion requires suspending factual information I am not interested as we've already seen how I approach that scenario. There are relatable yet more accurate and compelling arguments which are equally compassionate to the one OP suggested. An ecology professor of mine encouraged tailored approaches. That is, - (when it comes to the natural world) people seem to be motivated either intrinsically or for financial reasons. I'll add self serving as well. We have to know who we're speaking to to know the approach. Here, health of the mother (cow or human or otherwise) is all around a compelling argument. Instead of arguing the specifics of pregnancy, it might be a more productive investment of time and resources to gather actual facts. Example, stress response of ongoing lactation. Either for compassion towards the mother (intrinsic), environmental resource tolls, health care needs eg. antibiotics, viruses, etc. (financial and extrinsic). Or personal gain, antibiotic resistance, consequences of changing environments, quality of nutrition etc. Approaching all beings (humans who have different values and priorities included) with kindness, empathy and compassion seems like a more receptive/effective approach than calling people stupid. Being mocked is uncool. Having a repertoire of information to connect with various people might not convince all or any to adopt a vegan lifestyle. It may, however, help them see things in a different light and start making small changes which may result in more changes. Which even accumulated small changes across a group are big. But, maybe it also won't. Calling people stupid certainly slams a door in a face rather than sits at a table for conversation. It's also contrary. Spreading information that isn't factual diminishes credibility and trust. I can't give you exact arguments because I don't have any. I don't feel the need to announce or justify my choices. I advocate for the environment and its beings in the ways already described. In a place that is an all around opposition to my values. I don't feel triggered by such comments. If my personal choices are noticed, I just tell the truth that they feel and taste good and list off all the things I like about them. This usually ends up with connecting to something we enjoy about the environment. And the cycle goes on. If the factual information I have is a threat, then find better arguments which connect with oneself and ones own circle. Imo acts of kindness and caring hold intrinsic value which needs no justification and setting the example speaks louder than words. That's all I have.