Try to feed your crickets some good food (fish food?) for a few days before feeding them. That sure beefs their protein value

(when I buy crickets, they are mostly very thirsty and hungry. Every bit of food you put in your crickets, ends up in your ants, so its a good investment to keep them in a box a few days and feed them with good quality high protein food. I usually give them fish food, good supply of water and some fruit)