Hi there, welcome 🙂
Sometimes bunnies are skeptical of new foods, but once they try them a few times they will start eating them readily. This is probably an adaptation for them to not eat too much of something poisonous (they try a few bites and see how they feel). So as long as he’s not having any tummy issues, go ahead and keep offering it with his salad.
Parsley doesn’t need to be offered a special way, you just don’t want it to make up the bulk of the greens. I usually aim for no more than 30% of the salad as a high-oxalate veg, and I usually put it in a rotation so I don’t feed it every week.
The link to the HRS page (https://rabbit.org/suggested-vegetables-and-fruits-for-a-rabbit-diet/) has a bit more info on the amounts of things. So at least 75% of the fresh foods your bun gets should be leafy greens. I consider herbs to be leafy greens, as opposed to root veggies or fruiting parts of veggies (like bell pepper, zucchini, etc.). Non-leafy veg (celery, carrot, broccoli, bell peppers, squash, etc.) can be up to 15% of the veg, but personally I usually treat these types of veggies as treats. Then the last 10% can be fruits, but I also don’t regularly feed fruit. Occasionally my buns get a little bite of my apple or banana as a special treat, but you can think of fruit as like the ice cream of the bunny world.
For anything on the oxalate list, you can pull anything leafy and use it in your rotation. I aim for about 3 types of greens a day, with only 1 high oxalate veg. Rosemary and thyme (and other herbs) would fall in this group, and are a great way to add some enrichment to the salad. In my experience buns won’t eat much rosemary or thyme though, but they will take a nibble of it so it’s fun to offer, and it does make their salad smell very exciting! A salad of romaine, cilantro, and parsley would be great (and coincidentally is what my buns are getting tonight!).
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.