No, not all of the mass from the ingested grass is accounted for in the growth and waste of herbivore A. Some of the mass is lost or does not get utilized.
Let's imagine some key numbers:
Herbivore A ingests 50 kg of grass per day.
It provides 10 kg of waste (feces) per day.
Its body mass increases by 1 kg per day due to growth.
So the waste and growth accounts for 10 kg + 1 kg = 11 kg.
This leaves 50 kg - 11 kg = 39 kg of the ingested mass unaccounted for.
Mathematically:
Ingested mass (IM) = 50 kg
Waste mass (WM) = 10 kg
Growth mass (GM) = 1 kg
Utilized mass (UM) = WM + GM = 10 kg + 1 kg = 11 kg
Missing mass (MM) = IM - UM
= 50 kg - 11 kg
= 39 kg
So about 39 kg or 78% of the ingested mass is missing, indicating it is lost or not efficiently utilized by herbivore A. Let me know if this helps explain the concept!