Mealworms are packed with protein and can boost feather growth during molting seasons. According to Emous and Krimpen additional protein will help chicken regrow their feathers faster and can provide an extra boost for the immune system. Addiontally zinc can help decrease frayed feathers and blisters on the feather shafts. By providing extra protein, pecking in laying hens may be decreased as well.
When it comes to egg laying and egg production Mendonça and Lima demonstrated that an increase in protein will lead to faster egg production and egg weight.
Mealworms can help reduce our reliance on soymeal and fishmeal in chicken feed. Statsnik et al recommend up to replacing up to 4% of soymeal or fishmeal with mealworm meal. While small, more research is being conducted to see how higher levels of inclusions will effect chickens. A 4% inclusion of mealworm meal does not effect the quality of chicken meat either.
Deep litter systems can also benefit from mealworms. Chicken's will turn their own bedding digging for the mealworms, saving you the trouble!
Mealworms can also help train your chickens. They'll come running when you shake the bag.