On Feed Conversion Ratios... (FCR or FCE)

[jtcitrus]

So there's much ado about FCR's on the interwebs, but little useful information contained in them. FCR's are the pounds of feed for each pound of mass... but which mass?

animal weight?
dressed weight?
include any organs?
What about bone mass?
What about egg mass?


The relevant measure will vary based on your goal, but all of that information (breed/species averages) should be available somewhere right?

Common FCR's I see are
1.2:1 for tilapia/salmon
2:1 for chickens (does this account for egg mass?)
4:1 rabbits

I know there are other cosiderations: which animal parts become dogfood or fish food or worm/BSF food (which turns into feed for poultry, etc...)

Comments? Thoughts? Sources?

THANKS

 

[A.T. Hagan]

Usually it's pounds of feed to pounds of live weight. Most of the time it's pretty clear if they're talking about dressed birds and such.

 

[jtcitrus]

but what about the rest of the mass?
Is there a number that says Pounds of feed to pounds of live weight + egg mass? It seems to me that would be a more relevant number for poultry. What about meat and/or bone to live weight ratio?

I've seen a ton of individual listings for this breed/species or that breed/species spaced through out many websites, but never a comprehensive inventory.

 

[A.T. Hagan]

You would have to get down to the individual study to know if they were using some other sort of ratio. I have seen some broiler studies where there was some discussion of pounds feed to amount of edible muscle (meat). This is usually identified as such. Can't recall seeing one that took into consideration the egg mass within a hen of laying age.