There is a world somewhere between reality and fiction. Although ignored by many, it is very real and so are those living in it. This forum is about the natural world. Here, wild animals will be heard and respected. The forum offers a glimpse into an unknown world as well as a room with a view on the present and the future. Anyone able to speak on behalf of those living in the emerald forest and the deep blue sea is invited to join.
So the data on absorption begs question on whether it's worth correcting for food weight when the animal is not gorged. For instance, in a 19 kg meal, within the next 24-48 hrs 14 kg of that would be assimilated into maintaining tissue mass and other processes. Then there'd be about 5 kg of stool and colonic contents. Pretty much every mammal that is not in a starvation state has colonic contents at baseline. Therefore, colonic contents are essentially part of the organisms functional weight and removing them would be an unnatural modification.
Of course for gorging the subtraction would be warranted, but likely we have to subtract less. Remember, the hunters who liked to subtract gorged bait weight from cats never gave the animal a chance to assimilate 75% of the bait in baseline body functions, as well... they killed the animal.