Rabbits prefer alfalfa over grass hay, because alfalfa is richer. It is tricky to wean a bun over from alfalfa to grass hay, but you could cut back gradually on the alfalfa and mix in more and more grass hay. Rabbots can have any grass hay that’s good for horses. This time of year you could also perhaps find some fresh grass -start with smaller amounts. (If you’re in Europe or in the parts of the USA with known RVHD, its important to get Angel vaccinated).

How is his body weight, would you say? Is he still getting pellets?

You could try orchard hay. That tends to be a little softer and sweeter, but it is a grass hay. Bunnies love alfalfa because it tastes super yummy to them. But it is also very rich and shouldn’t be fed regularly to adult bunnies. As a treat, I will give my bunny a hay cube with oat and alfalfa hay. He prefers orchard for his regular hay. He’s not a big fan of timothy. Sometimes you just have to experiment to see what they like.

It is often easier to transition a bun from alfalfa pellets to timothy pellets, so you could start with that transition if you haven’t already. They only need one source of alfalfa when they are growing.  They also sell pure timothy pellets for horses, you could try to incorporate those as a way to boost his timothy consumption in the meantime. Not sure of his exact age, but if he’s over 6 months you could start reducing the amount of pellets fed.

Sometimes it just takes consistency and patience. If you keep mixing the alfalfa with grass hays (Oat is another good one to try), eventually he will likely take a nibble. Then you can start slowly reducing the amount of alfalfa and increasing the amount of grass hay.

Fresh grass is a great idea as well, you can grow cat grass/wheat grass for him if you can’t find a good source outside.