Hmm, so that tropical carnival rabbit mix does not look like a healthy pellet. Typically the types that look like granola or museli tend to be too high in fat, protein, and starch, and can encourage selective eating. They basically include a lot of junk food, that the rabbit will fill up on and then not eat enough hay. How big of a pellet ration does he get per day?
I think to start, since he is still eating some hay and greens, I would reduce his pellet amount by half. You can also pick out the seeds, grains, and other “treat” parts, and leave just the pelleted parts (also, sorry if I am looking at the wrong pellet, I just googled that pellet brand).
Then monitor him to see if his hay intake increases (it should). If that helps, I would slowly start transitioning him to a better pellet. Look for one that is just pellets, not the types with seeds mixed in. Some popular brands that most buns do well on (and fit the nutritional recommendations pretty well) are Science Selective, Sherwood Forest, and Oxbow Essentials.
The other thing I wanted to point out is that rabbits shouldn’t have too much spinach. It’s OK in a rotation with other greens, but it has high oxalic acid content and can contribute to some health issues.
With any change in diet, it’s important to make the change slowly and monitor carefully. It’s generally easier to remove something than to add something, so it would be OK to reduce the pellets and reduce spinach, and then slowly introduce some new foods once his hay intake improves.
You can see some more info on recommended diet, including pellet info : https://binkybunny.com/infocategory/healthy-diet/
Here’s a suggested veggie list: https://binkybunny.com/bunnyinfo/veggie-list/
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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.