I think the sunflower product is a fat extracted meal made from de-hulled "seeds". Then the total crude protein would approach 30%. Same product when consumed by something like a human has a digestible protein of about 23%. I would trust the nutritional value for sunflower seeds as developed for chickens of the life-stage in question rather than extrapolate from something like a horse. Problem you may run into even then is our birds living under more varied conditions may be more or less efficient at using a given foodstuff.