Calories definitely do count. You are correct that there can be a big difference between different proteins and the different brands. I would check the calorie counts on everything you feed and feed the amount by a calorie basis. Ex: 1 large patty of S&C Duck Duck Goose has 285 cal while the Surf & Turf has 470 cal. Your dogs could be getting way more calories than they need which could explain the weight gain. I would try to determine how many calories you need to feed them per day to maintain the right weight and feed that. You’ll end up feeding more of one food and less of another.
