I read that soybean products can interfere with digestion in chickens. Is that correct? I started my girls on purina start and grow but when I looked on the bag for nutritional infomation they gave a web address for detailed information http://www.poultrynutrition.com/. I searched that site and found their detailed info for start and grow and it did not offer detailed info specfically where the protien was derived from. They then tell you to contact the manufacturing plant. Their webpage containing that comment is below; http://www.poultrynutrition.com/OURPRODUCTS/Products/StartGrow/default.aspx ANIMAL PROTEINAND FAT-FREE. Contact your local manufacturing plant for a current feed tag. Maybe this is not that imprtant but it is to me. Can some one set me straight. Should I steer away from feeding my girls protien derived from soybean. I guess souybean is used a lot because of it's high protien content but if I'm am correct it is not complete protien so they add the missing elements? Correct?