He should be eating hay above all else. Completely cut out carrots from his diet because it’s something he shouldn’t be eating regularly. Carrots are actually full of sugar and they will reinforce his lack of hay appetite because carrots are much more appealing. Present a small amount of lettuce in the morning, and on he’s done, take away the dish and leave him with only hay. Hay should always be out. Don’t feed him again until you give him pellets at the end of the day. 80% of his belly should be filled with hay, not veggies or carrots.
You need to adjust non-hay food presentation to cater to more hay eating. This means leaving a lot of time where his only option for eating is hay. Without hay, his stomach tubes will clog up and he will suffer a lot of gas, develop GI stasis, and potentially die.
How old is your rabbit? It’s good just to have a review to make sure your rabbit has the correct diet as he’s growing up!
Read the diet info at https://binkybunny.com/BUNNYINFO/tabid/53/CategoryID/2/PID/940/Default.aspx to see what’s needed.
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.