The only thing that stays the same with bagged feeds is the name on the label and the average nutritional values stated on it. Exactly what foodstuffs go in can and does vary with each batch, depending (usually) on what was cheapest when they were sourced.
If your flock is a bit overweight as you said in #6, they're probably consuming too many carbs, from maize/corn in the feed in all likelihood. Protein is the most expensive component in so-called complete feeds, so naturally the manufacturer will reduce it to the least possible quantity and bulk out with cheaper ingredients.
