Rooster booster is made by the same people that make poultry Booster. Many have used them with good results so it's a quality product. Bit no I have not used either one.
I did my research on vitamin packs years ago, and the one I linked above was best for me as it had the most Niacin for the...
Feeds are generally formulated for different parts of a birds life. Such as starter (generally about 20% protein, 1% calcium), grower / maintenance (14 to 18% protein, 1% calcium), and layer (16ish% protein, 3% calcium). The name on the bag of feed let's you know what stage of life it's intended...