It is important to note that rabbits tend to hide signs of ailing health because they are prey animals. This self-preserving instinct to hide illness lives on in domesticated rabbits, so it is critical to continually monitor your rabbit for any changes in behavior.
Rabbits need hay in their diets to support their digestive system, and timothy hay is best for the teeth of a Holland Lop. If their pellets have alfalfa hay, do not give additional alfalfa hay. You can give occasional treats to adult Lops but avoid giving them to juveniles.