Factor in standard temp in Po-Boy and that could well make up most of any difference. Temp plays a huge part in metabolism in cold-blooded fish. Bruce's RAS YP kept growing over winter because the Temp in the RAS was not Neb. cold. I thought they got some natural food also (worms , FH, etc ).

When it gets to hot or cold metabolism slows down and food use conversion changes from optimum temp range. In the RAS you stay in the optimum temp range and metabolism stays high as does food conversion. You want to add flesh not fat from sitting around as it weighs more . But this is not a grow fish for feeding people (aquaculture) operation so is food conversion really that important ? There are lots of studies with different ways to measure weights -- wet to wet , dry to wet, dry to dry. IIRC they mostly end up with dead fish. Not my idea of the right place for a prize CSBG . I don't think you can get accurate food conversion rates in a pond where the fish are eating natural food ; all you can do is take the controlled study rates from the studies and extrapolate it to how much food you put in the pond and what to expect to see resulting from the fish . As a pond management tool it is an estimate of what to expect , not a measurement of results. I would suggest that what Bruce is doing is better - take avg growth rates , sizes and weights along with the # of fish and calculate weight of fish to amount of food -- and then you know "How much did the food help" aka How many pounds of extra fish did I get with X lbs of supp. food. Do this in a rough way by comparing your fish to Std RW fish or your fish from a non-feed pond to the feed pond.